This is a little more niche, but as a hobbyist guitar player, I’ve wasted a ton of money on gear that had some use, but was mostly redundant or not all that necessary.
But the best purchase I ever made for guitar gear was a Digitech Trio pedal. There was a blow out sale with one of the major music vendors and they were just giving them away for $50. I don’t get a chance to play with other folks all that often, and especially over the whole Covid lockdowns, this thing made at-home play/practice just the most fun thing ever. The pedal generates drum and bass parts that will fit whatever chord progression you feed it, so it just fills in the whole rhythm section and you can do whatever you need on top of that.
It gets more use than any other piece of gear I’ve ever had.
you know, I went to SpaceDicks one time. The first thing listed there was a link to another subreddit that was entirely pictures of horse dicks. It was around about that time that I reached the conclusion that SpaceDicks wasn’t for me.