Mistakes I’ve made

Well, one relative I loaned stuff to is dead, and another relative I loaned to I refuse to have anything to do with anymore for other reasons

That’s a start 

I clicked a link to ASR thread once, insane.

Imho, it sounds like your friends confused loaned with gifted.  Since this has happened on multiple occasions with different people, perhaps you should make your intentions more clear.  

I cannot imagine throwing a borrowed turntable in the trash.
But then, I've never loaned (or borrowed) HiFi gear.
On the other hand, if you've never made expensive mistakes in this hobby, then probably you're either very young, very lucky, or you're not trying hard enough.

Some of my biggest mistakes involved buying mid-priced compromise gear. I haven't fallen for too many expensive snake oil gimmicks, though. I did once buy a $500 set of isolation footers for my speakers, which did nothing much but make them wobbly. That was easy enough to fix by sending them back.

What's the opposite of expensive mistakes? Moving your speakers (or listening chair) a few inches.

@testpilot 

I've heard this when confronted-

"Oh, you already have a really nice stereo- I never thought you would want your ______ back"