For me was about 45 years ago, I bought a Bronica S2A SLR. I kept it for about a month and sold it at a significnt loss.
For those too young to remember, Bronica used the same square box format as Hasselblad. It had a complete system available for it. But instead of putting an expensive shutter in each lens, it used a giant focal plane shutter. Which sounds like a great idea. . . Until you pressed the shutter release! the weight of the giant mirror flapping and the sideways torque of the focal plane shutter caused the camera to practically jump out of your hand. It could only really be used on an extremely sturdy tripod.
It was a studio camera, and I was young and dumb, and definitely not a studio sort of guy.
Too many to remember, I’ve always bought things on a whim and often regretted it.
My first was probably a bit like yours; I used TLRs as a youth and… on a whim… bought a Soviet Hasselblad look-alike, the Zenith 80. I had exactly the same reaction as you.
More recently I’ve wasted a fortune changing mirrorless systems numerous times only to end up back where I started - micro 4/3.
Most recent was my re-acquisition of an Olympus 17/1.8. a lens I’ve owned (twice!) in the past and never really liked. I bought it because it doesn’t really have any competition at this focal length and hoped I could live with it this time but of course I couldn’t. I replaced it with a Panasonic 15/1.7 but I really would have preferred a 17.
I don’t worry about it though, it’s just how I’ve always been.
Probably the Tamron Adaptall-2 SP (31A) 200-500mm F5.6. It’s not even a bad lens - it’s actually pretty good for what it is. But I already had the much lighter and sharper Pentax A 400/5.6 and loved it… I had a weird obsession with getting to 500mm.
I eventually sold off the Tamron (at a big loss) and I hope I’ve learned the lesson of not making a specification my goal, rather than something to help me make photos.