Mistakes I’ve made

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"

When I went into the service I loaned a complete system (receiver, TT, speakers and a few records) to a friend.  It was the 70s, I was young and it was a 10 year old Radio Shack system, but top-of-line for them.  I come back from overseas and he is married and at a BBQ at his place with many people he announces to everyone what a great wedding gift I had given them!  I was essentially apoplectic.

That was the first and last time for that sheeit!

The flip side is while overseas I bought quite a bit of "very good" stereo equipment, but had yet to receive it as part of rotating back to the states.
Still have some of it. And yes almost 50 years later it still sounds excellent.