It pays to be skeptical but this was a super unique situation with cofounders with different goals and a very unique (absurd?) structure. Wikipedia and Wikimedia worked. Lets not throw the baby out with the bathwater.
Wikipedia is mostly written by its users though. Wikimedia is just a glorified site host, if it went rouge the encyclopedia could simply be forked and hosted elsewhere. Microsoft has the right to build on the GPT trained models but others do not, they'd have to start from scratch.
You shouldn't trust corporate entities, you should trust the people that run them. The people in charge can always do what they want, at least for a while.