How can I make sure the next hedge fund I interview at know I'm a mediocre guitar player? Or is mediocre not worth mentioning?

I found electrical engineers to be similar.

Computer science degree holders were mostly lacking ability in my experience.

But I wouldn't count anyone out by their degree.

The best people in any field are the ones that passed the harshest filter, and pole vaulting from music to programming is about as demanding as it gets.

Not as much as you'd think. Most of them had a specialty in computer music which leans heavily on building your own tools/instruments.

But I agree with you.

Some of the best developers I’ve worked (and work) with are from a music background with an interest in computer music also. I guess maybe part of it is that at a certain point in writing music software you really need to be using C++, and audio software in particular is quite unforgiving due to its real-time nature, so you have to learn some fundamentals to write performante code? But I’m sure there’s more to it than just that.

I’ve also worked with some really smart people from a physics background.

Yeah I think that's mostly accurate. I also think that learning signals processing/sampling teaches you an enormous amount of practical, transferrable skill.

Similar kinds of problems come up in physics, so for me this tracks.