I understand your thoughts.
However,, over the decades,, I've found I can remember the ones that "got away" much easier than the ones I was chasing at the time.
Besides,, if you go back, with cash,, and haggle a good bit,, getting them to come down, then they can become trade fodder,, "just in case." (Although,, I usually just buy & not trade or sell.)
I could have bought a few things this past weekend at the OGCA show. But I knew a certain gun was in the wings. The owner & I were able to reach an agreement on a price, and the gun came home with me. BUT,,,,,,,, I also chose to NOT pass on another gun,, just because the price was too good to pass up. I didn't need the second one,, but I would have regretted it if I had not bought it. I bought the second gun,, well ahead of my negotiations with the seller of the one I wanted. It made my gun funds a little tighter,, but I was able to buy both the gun I really wanted,, a gun I didn't need,, and yet,, a 3rd gun,, not originally known to me,, but definitely one I was glad came up.
I came home without any regrets at myself for "passing" on anything.