I do regret selling a few treasures, but for the vast majority of the things that I have sold, I'm perfectly fine. I'm not the same person I was when I acquired them. Yes, I bought them for a reason back then, but those reasons are no longer valid. I'm in a different part of my life now. "Stuff" doesn't have the same importance and it can be liberating to lighten up.
I would also add that at long last I am wealthier than I ever imagined I would be, but it is kind of a hollow victory, as there really isn't much that I want to acquire, and covid put the brakes on travel desires.
In some ways, I'm exactly the same person that I've always been. I could have a fleet of Ferraris, but a Honda Accord suits me fine. Recently, I tried to get excited about a new Mercedes, but my practical side won out. Do I need one just to go the few miles to the local market and Home Depot, and I'd be worried about careless people running a cart into it?
The OP is right about one thing. Don't sell something that is a known treasure to fund a new treasure that you haven't even discovered yet.