Back in 2021 I stumbled on a ridiculously cheap used Sigma 4.5mm circular fisheye for APS-C cameras. I only had it for a few weeks and only took it out a few times. It was fun to use, in its way, but also very hard to use. There is so much going on in the frame that needs wrangling, not to mention keeping your feet (and in my case, belly) out of the shot. And, of course, no cropping, ever.
I bought that lens to sell it. I got 3x what I paid for it. Apparently it's popular with astrophotographers. But I sold it particularly quickly. After using it a few times I thought, OK, if I use this a couple of more times, I'm going to become "The Fisheye Guy." I didn't want that.
I do kinda miss it though. I made some striking pictures with that lens. It would be fun to take one out again.