I've worked with a guy that didn't finish his studies (started working out of university/ during 1st year and completely neglected it until they expelled him).

I've worked with a guy that didn't finish his studies (started working out of university/ during 1st year and completely neglected it until they expelled him). He was surprisingly good though as in he had a solid theoretical foundation, knew the inner workings of a compiler (this was relevant for the project we worked on) etc. Also at my former company there was a principal computer scientist who was quite proud that he didn't have a university degree; I didn't work with him much but he was obviously fairly accomplished, career-wise. So that worked fine for him. Most people are not like that, though; even though in theory you can study everything by yourself nowadays, I find that in practice people who didn't go to university often tend to have a fairly narrow & shallow field of expertise ("narrow" = don't have experience with many different things/ often focus on one language and a few sets of related technologies; "shallow" = they often don't understand too many layers of abstraction, and get completely lost if they need to go too deep). This is perfectly fine at the start of your career, but as years go by (like, 20years in, when you're still only mid-career) I can't imagine this working too well; unless maybe you switch to management?