Researchers have pointed out at a "trend towards centralization". Although bitcoin can be sent directly from user to user, in practice intermediaries are widely used.[31]:220–222 Bitcoin miners join large mining pools to minimize the variance of their income.[31]:215, 219–222[111]:3[112] Because transactions on the network are confirmed by miners, decentralization of the network requires that no single miner or mining pool obtains 51% of the hashing power, which would allow them to double-spend coins, prevent certain transactions from being verified and prevent other miners from earning income.[113] As of 2013 just six mining pools controlled 75% of overall bitcoin hashing power.[113] In 2014 mining pool obtained 51% hashing power which raised significant controversies about the safety of the network. The pool has voluntarily capped their hashing power at 39.99% and requested other pools to act responsibly for the benefit of the whole network.[114]
However, that being said, cryptocurrencies are unique in that clever marketers can make a profit doing exactly that, giving away money. This would not be possible in other currencies, where they simply can’t be broken down small enough. The operator will usually make less than a penny. If they were forced to give you a penny or more, there’d be no way to be profitable.

One of the Bitcoin blockchain's most innovative aspects is how it incentivizes nodes to participate in the intensive consensus-building process by randomly rewarding one node with a fixed bounty (currently 12.5 BTC) every time a new block is settled and committed to the chain. This accumulation of Bitcoin in exchange for participation is called "mining" and is how new currency is added to the total system afloat.

A blockchain is a record-keeping system where multiple sources validate an entry before it gets added to the chain of data. Once data has been added, it cannot be changed and the record is distributed to multiple places within the network. Adding a new record (known as a block) to the blockchain sequence requires verification by multiple members connected to the blockchain network. These blocks of data are all linked to one another forming the chain. All transactions are public to those in the blockchain, but all individual identities are hidden.

A prospective miner needs a bitcoin wallet—an encrypted online bank account—to hold what is earned. The problem is, as in most bitcoin scenarios, wallets are unregulated and prone to attacks. Late last year, hackers staged a bitcoin heist in which they stole some $1.2 million worth of the currency from the site When bitcoins are lost or stolen they are completely gone, just like cash. With no central bank backing your bitcoins, there is no possible way to recoup your loses. 

The technological complexity is explained nicely to a degree which is necessary for the user to understand roughly the whole block chain as a system. Explaining a car and its advantages for humans would start also by describing wheels, motor and steering by hand. A car user does not need to know the details of a motor , electricity etc. He looks at how to move, security, velocity etc.
Theoretically, it is possible for a hacker to take advantage of the majority rule in what is referred to as a 51% attack. Here’s how it would happen. Let’s say that there are 5 million computers on the Bitcoin network, a gross understatement for sure but an easy enough number to divide. In order to achieve a majority on the network, a hacker would need to control at least 2.5 million and one of those computers. In doing so, an attacker or group of attackers could interfere with the process of recording new transactions. They could send a transaction — and then reverse it, making it appear as though they still had the coin they just spent. This vulnerability, known as double-spending, is the digital equivalent of a perfect counterfeit and would enable users to spend their Bitcoins twice.
People, don’t be fooled by the apparent advantages and usages of Blockchain technology or Bitcoin, it’s what you don’t know that is destructive to you personally and to society in general. It is merely another way to control you through information, to hack into your private lives and the only ones that truly benefit from this technology are the global wealthy elite, the greedy, materialistic oligarchs of global chaos and conflict. Bitcoin is virtual money, it doesn’t really exist except on the computer!

Bitcoin’s first mover advantage, popularity, and network effect have cemented it as the most popular cryptocurrency with the largest market cap. Rivals like Litecoin may have numerous technical advantages over Bitcoin’s algorithm (see more about that here), but they only hold a fraction of Bitcoin’s market cap and their dwindling communities largely consist of loyalists, speculators, and antagonistic anti-Bitcoin buyers.
Peer to peer Bitcoin lending websites with listings from various borrowers are another option. Bitbond is such a peer-to-peer lending site. Borrowers publish funding requests and you can contribute to their loan. You can fund small portions of many loans and thereby diversify default risk. Bitcoin loans usually work the same way as fiat currency loans. The borrower gets a certain amount of money over a specified time and repays the money with interest. There are two things you need to be aware of when you lend Bitcoins. The site needs to be trustworthy and the borrower needs to be trustworthy. When the site assesses the creditworthiness of their applicants the information given about borrowers can be more credible.
By mining, you can earn cryptocurrency without having to put down money for it. That said, you certainly don't have to be a miner to own crypto.  You can also buy crypto using fiat currency (USD, EUR, JPY, etc); you can trade it on an exchange like Bitstamp using other crypto (example: Using Ethereum or NEO to buy Bitcoin); you even can earn it by playing video games or by publishing blogposts on platforms that pay its users in crypto. An example of the latter is Steemit, which is kind of like Medium except that users can reward bloggers by paying them in a proprietary cryptocurrency called Steem.  Steem can then be traded elsewhere for Bitcoin. 
Getting Bitcoin blockchain explained is essential to understanding how blockchain works. The Bitcoin blockchain is a database (known as a “ledger”) that consists only of Bitcoin transaction records. There is no central location that holds the database, instead it is shared across a huge network of computers. So, for new transactions to be added to the database, the nodes must agree that the transaction is real and valid.
The bitcoin blockchain is a public ledger that records bitcoin transactions.[67] It is implemented as a chain of blocks, each block containing a hash of the previous block up to the genesis block[a] of the chain. A network of communicating nodes running bitcoin software maintains the blockchain.[31]:215–219 Transactions of the form payer X sends Y bitcoins to payee Z are broadcast to this network using readily available software applications.