I started programming at gymnasium and through uni. Throughout uni I did a lot of Competitive Programming. Most programs in CP are written and discarded within hours of each other. You also pretty much only use the standard library and no third-party tools. You never interact with the hardware of the system that the program runs on. Maybe reading files from the filesystem (depending on judge software) but definitely no networking. No threading or parallelism. No CI/CD. No Docker, K8s. No build systems. No project management & other "soft knowledge". No "Does it work on IE8?"-stuff.

Essentially you become an expert in writing 100-200 lines of code that reads data from standard input and prints data to standard output. Useful for CP, not so much in the real world. After doing CP as a hobby for a few years at uni I realized this and instantly looked to my peers. What were they doing? One guy was building something similar to IFTTT in golang. Another one was building his own window manager for Linux. Some were really good with constructing websites. But what except solve toy computer science questions could I do?

I don't come with any specific advice, but the way you described being down in the dumps felt very similar to my experience. I think that kind of experience is quite common and normal... Maybe more people have had such a moment than not? I hope you manage to find a way were you get to do what you love.