It's hard to leave when a huge chunk of your interpersonal connections are tangled in its web. It's the same reason Facebook and Twitter still exist.
That's part of the reason why these platforms have such high valuations per capita, opposed to non- or less-social apps. There's a lot of momentum.
I host a Matrix server myself and even I still use Discord more because that's where people are. Matrix has its own issues and, frankly, it's a shitshow; discord offers a lot of features with better UX and it has a lot of people.
The only reason Skype and team speak died* was because Discord provided a better value. Now it has the momentum, and the only way it will die is if something else offers even more value. Enshitification helps shift, but the momentum fights against it; momentum is like a small multiplier on top of its feature value.
Even if the app enshitifies, even if their base value drops; the product is still larger because of the userbase. So it becomes a chicken and egg problem. Until an inflection point is hit, their sheer mass buys them room to enshittify.
People who can walk away early are the exception, not the rule. It's why people still use Reddit more than Lemmy. I may get some hate for this, but I don't think the people on Lemmy are inherently "better." There are selection biases, and I'm sure that holds true by some metrics, but not in totality.
"If everyone accelerated at the same time, there wouldn't be a traffic jam" is true, but that's not how the world or its people work; you just need to come to terms with that before you can do anything about it.
Edit: speech to text typos. Probably missed some.