Upwork can work for very niche things as a extra channel. I've seen it work for people selling packages of "I'll fork bitcoin for you for 2k". For normal contracts it's terrible.

I started on freelancer websites when I was 15 and it was nice to bag 20$ per hour plus extra if I happened to be faster.

But the more experienced you get the more you can charge and use your network instead of cheap jobs on Upwork.