Every single Lemmy instance could theoretically be doomed to repeat Reddit's path. Including the flagship instance, lemmy.ml. Theoretically.

However, once said instance is going downhill, people would be far less affected. Because only a fraction of the users and communities will be in that instance; most of them will be elsewhere. And since the instances work under the same protocol, it would be way easier to move the info elsewhere too.

And the admins of those instances know it. That discourages them to be abusive towards their own users, because unlike the Reddit admins they can't rely on people coming back.

That's the beauty of the Fediverse. We aren't putting all our eggs inside the same basket, but even then we can make a tasty omelette together with all of them.

It could happen if there was a very popular instance that didn't federate with others.

Offer a large sum of money to whom and for what? To an instance owner? Okay, take your instance, the users will migrate as soon as you start making changes that they don't like and you can't stop them. Also, good luck monztising it because either you have the same problem reddit had in that third party apps don't show ads, or you disguise ads as content and now your users hate you and migrate away.

To the développers? To do what exactly? If it's to make the source code private, tough luck not only are they not allowed to do that thanks to the licence, but also that would be literally impossible due to the amount of copies. If it's to implement changes to make money, as soon as instance owners, who are users and are interested in not having their users migrate away from their instance, see that, they won't update and someone will continue making something out of the last good copy of the source code, forking it.

There is effectively no path for someone to pay to take over lemmy, apart from bribing every user (and even that wouldn't prevent me from taking the bribe and just going back to what we were doing)