We can not control bitcoin unless you have more than 50% ownership of the bitcoin. But there is nothing like that. Altcoins are following bitcoins due to money distribution. Because most of the owners of the altcoins are investing in bitcoin. When they get some profits, they will invest in altcoins. So the altcoin prices will increase.
There's no need to have more than 50% of hashrate to control bitcoin. You can control it even if you have less than it as long as you did collusion to the another miners. This problem was happening since a long time ago where miners were always making collusion to take over the hashrate and they will able to reject or approve the improvement proposal. This is making bitcoin unhealthy. I don't like miners. Miners are nothing without buyers.