I have doubts about bitcoin decentralisation from a long time. I know miners are also play a big roll in bitcoin. But honestly I don't have a full knowledge about bitcoin so lots of things confused me.and I know many of you guys also have many confusion about bitcoin and some of even don't know much.and today I am reading an article on IOTA doublspending issue and wrong assumption of many people. So I am post some main point here and put a link a full article.
Seriously I like this question
"Is there any currency, asset, system, good, piece material on earth that can’t be misused or manipulated in any way?"
" if attackers would get control over 51% of the hash-rate, delivered by miners, they can doublespend as they like, because:
“Since the attacker can generate blocks faster than the rest of the network, he can simply persevere with his private fork until it becomes longer than the branch built by the honest network, from whatever disadvantage.
No amount of confirmations can prevent this attack; however, waiting for confirmations does increase the aggregate resource cost of performing the attack, which could potentially make it unprofitable or delay it long enough for the circumstances to change or slower-acting synchronization methods to kick in.
Bitcoin’s security model relies on no single coalition of miners controlling more than half the mining power. A miner with more than 50% hash power is incentivized to reduce their mining power and reframe from attacking in order for their mining equipment and bitcoin income to retain its value.”
Full Article :- http://www.tangleblog.com/2017/07/10/is-double-spending-possible-with-iota/
I am sure this article give you much more knowledge in short. Happy reading.