Ask HN: Software engineers that came back to school

Hello, so I graduated with a bachelor's degree in Economics and Finance and after bouncing around odd jobs I learned to code - long story short I am now a software engineer with 6 years of experience.

I like my job, but the more I learn the more I go into the field the more I am drawn to the theoretical side of things, especially in distributed systems. An idea was brewing in my brain of maybe going back to university and try to get a PhD, maybe even do it somehow while I'm still working. But since my BsC is old and not in CS I was wondering if it's even an option without going back. And maybe I've waited far too long

Has anyone had any experience of going back to academia to study Computer Science after some years in the industry? How were the experiences? Was it worth it? Should I just learn on my own (I don't lack the motivation, I love learning) ?

Thanks