I mean, you're right that something is broken, and it's that nothing can last without inevitable enshittifaction in for the sake of maximizing moneymaking.
It's really simple: message boards are just a really basic thing where people want to talk to/at each other at a less frantic pace than a chat room, and the reality is that if they're left at that and just that basic thing, they're never going to make much money, if at all.
Making money off of them inherently requires turning/growing them into something beyond a basic message board. It requires ads, a bunch of additional features, articles, "pivots to video," social media, etc., etc.. So you basically have to turn it into something that doesn't appeal to most of the original user base, likely driving them away in the end, and you're trying to play catch up with the myriad of other time sucks out there that already more appealing to begin with. It's a lose-lose proposition.
Like, some things just don't make money. This place will likely never make money in anything even remotely resembling its current or previous forms. That's just how it is. If that doesn't work for you, you should either sell it or fold it, instead of trying to turn it into something it's not.