Miners are unable to steal money that was never sent to them, and they can’t force full nodes off of the network
Choosing ASICs for Sia
David Vorick

That was true until segwit: since segwit uses anyone-can-pay transactions, a majority of miners could collude and steal users’ funds.

This changes a fundamental Bitcoin rule and is one of the reasons why implementing segwit with a softfork is much worse than an hard fork that could also not create technical debt.