So I'm new to this. I learned %51 attack is possible but not likely because whole ecosystem is affected and pool owners don't want that. I checked https://btc.com/stats/pool and I see 2 pools have more than %50 power. Isn't it bad for ecosystem? Why do miners stay in 2 big pools and give them more than %50 power? Even if they don't use it for evil.
Foundry USA: %27.2 Antpool: %24.5
Wouldn't it be better if total of the biggest pools are less than %50? Would you prefer 4 pools for %50 rather than 2 pools for %50?
To wipe out your fear, you must read some articles. I hope you will read those articles but to summarize, there are some big mining pools that have big hashrates and some pools were believed to owned by same owners. They did not do any attack when they had chances because your fear shows the reason, they will not get benefit by doing this. Bitcoin network is decentralized and is believed to safely against attack that makes its high value. If any attack happens, its price will be destroyed, drop a lot and mining pools will be in the hell too. They don't need hell as they have a lot of capital spent for their mining farms as well as hold many bitcoins.
There are some insightful information and charts in those articles for dominating, big mining pools.