I'll take the hit here.
I thought electric vehicles were a really dumb idea. Too many problems to be solved for. Range. Charging. Depreciation. Getting people to switch. All of the other infrastructure. Now it's what everyone does, and Tesla is (last I checked) one of the very few EV makers that is able to make a profit on EVs, while upstarts in the space (including Ford) are losing money on every EV sale.
I thought self-landing rockets was a dumb idea.
I thought Starlink was a dumb idea.
I think a lot of what Elon is doing now is a very dumb idea, but as a Twitter user with friends across the political spectrum, I have seen what has appeared to be a suppression of speech that largely affected my right leaning friends, while my left leaning friends gloated about it. I've watched journalists like Taylor Lorenz break the rules with impunity while journalists on the right were deplatformed for doing less.
This is clearly a departure, and I would argue that many right leaning friends were hoping that Elon would stop the pendulum swing, I don't think any were expecting the pendulum to swing back the other way so hard. Elon's actions have seemed arbitrary, but a) Every change looks bad when you don't know their motivations, and b) I've been wrong about Elon's entire life to this point.
It's possible that he's done surveys or polls or gotten data indicating that fear of doxxing is a thing that is meaningfully suppressing Twitter engagement. It is possible that he knows what he's doing, but it isn't what he's said he's doing and it definitely isn't what we expected him to be doing.
I don't know the answer to those questions, and so I don't know if he's ruining Twitter or just transforming it into something that it hasn't been, and I'm mindful of the fact that practically every single change that Twitter has ever made has been received as "the end of Twitter," from verified accounts, to changing their API ToS, to blocking apps, to suing users with any vague reference to 'tweet' in their apps, to bookmarks, analytics, 280 characters, etc., etc.