Satoshi addressed this scenario on page 4 of the bitcoin whitepaper:

"If a greedy attacker is able to assemble more CPU power than all the honest nodes, he would have to choose between using it to defraud people by stealing back his payments, or using it to generate new coins. He ought to find it more profitable to play by the rules, such rules that favour him with more new coins than everyone else combined, than to undermine the system and the validity of his own wealth."

If they will unite then there will be a mining monopoly. This will be problematic to the community if this new group monopolizing the mining will be greedy and will try to place new rules on the system on their favor. But if they will follow by the rules then there will be no problem since this will mean more cheaper and faster transactions. But there is still danger if they will not abide by Satoshis rules.

Yeah that may really means killing of goose that lays the golden eggs but don't you know that bitmain is going to release asic miners for ethereum? That will destroy GPU mining and it means killing of geese and it's golds together.
I know what's reality and what's not. Because of that I wan to turn some fantazy and and imagine situation where they share 60% of whole hashrate and no private miner is going to leave them, they are as faithful as ever.

I'm certain Bitmain has controlled well over 51% at certain points. They no doubt have proxy pools and mining operations kept quiet. There's enough ill will against them that in the case of an attack freezing them out would be pretty much the only thing every single person in Bitcoin could agree on.

They may want to monopolise everything, but they also know their monopoly relies on the rest of the community. They don't operate in a vacuum.

bitcoin Some people have their own miners' engines to mine while others join an open pit pool where they combine their efforts to increase their chances of getting bitcoin

This is my same line of thought. These mining companies are so unbelievably rich just because they "own" Bitcoin, but in the very moment they would play dirty with it they would kill their Goose That Lays the Golden Eggs.

back in satoshi's day (cpu mining) the concept was:

if a miner could out pace other miners then that miner can then make some nasty changes. but that concept was flawed because it would need the community as a whole to accept the block as valid and not reject it.
which is where the concept was extended to explain that if other nodes who CPU mined also had the same new code and over many blocks there was a clear majority of which blocks were accepted over all. then that majority became the main chain. and most users would need to react and either update their node to join.. or if the new rule was nasty. not upgrade and just treat it as an altoin of more hashpower but less real world utility(not let merchants adopt nasty new rule)

same thing for GPU pool mining. even if many miners grouped together to out hash the rest of the community. the main payment services (coinbase/merchants/bitpay/exchanges) needed to also have the code for the new rules otherwise the blocks were deemed invalid and pools couldnt spend their rewards with their favourite merchants/services

the worse to occur was high reject/orphan rates which eventually gets the rule breaking pool IP banned and thus they only communicate with their like minded peers.thus making their own altcoin. the community that sticks to the old rules may suffer a delay in the average block time until difficulty adjusted

now that mining is no longer '1 node 1 miner' because ASICS dont hold the blockchain and nodes dont themselves mine directly. pools really do need to persuade the community to download a new node client version, with the new rules for the blocks to be acceptable.

this is why running a node is important. pools could make blocks of 200coin reward. but if no one in the main communuty accept such block. a pool cant really spend that block and thus they are wasting electric and ASIC hashtime making blocks the community (metaphorically) throw in the trash within 2 seconds

this leads to the 'rule breaking' pool to decide to either carry on with their altcoin and then develop exchange/paymnt service relations with merchants to accept their new coin network.. or stop mining the new rule (kiling the alt) and going back to mining the old rules just to atleast have the normal block rewards accepted by merchants, to cover pools mining costs

If they capture more than 50% of the coins, they will control the market
but it is not exactly 

You mean 30% miner vote not community vote, correct? I believe the USAF changed all that. Some people would say it was S2X, but that is highly arguable. From both sides, to be fair and unbiased.


Core abused? Can you explain more? You do not mean the USAF, do you?


We cannot control the people on what implementation they want to run. You can blame the community for wanting to run Core's software, not the developers.


Peter Todd also tweeted that there was a Greg Maxwell talk where Greg said that changing mining algorithm would be to the advantage of the Asic companies because they would always be the first to put out new Asic mining hardware to the market.


Maybe because Core is undeniably the best? Although I would like to see another team try to be the best.