Mistakes I’ve made

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.

I remember being mesmerized by hifi gear in PX catalogs in the 70's

Lot's of Mistakes in my life.  "Loaning" out motto,
"Never loan out anything I or you are not willing to give away"
Stereo equipment, tools, money, frying pan...

OP: Never regret being generous. It's a an admirable character trait and you will be rewarded many times over.

+1 @kingsleuy
+1 @middlemass
Stuff and money comes and goes, but what should be a higher priority is relationships.
Generosity is a great virtue, but it must be tempered with wisdom.  For instance, if a guy keeps running out of money because he cannot control his spending, he cannot distinguish his needs from his wants, then any additional money won’t really help his problem.  If it is a loan, you’ll only be adding to his burden which he cannot pay back.