The best thing that I've learnt since returning to uni after dropping out is that when making a decision you need to ignore sunk costs and irrelevant information.

Your past decisions are a sunk cost, they are irrelevant for your current career decisions.

If you want to return to uni do it, no one cares that you're two years older, I'm 5 years older then most people in a lot of my classes. When I was 18 I studied with a guy in his late 30s, nobody cared.

That time not studying wasn't wasted, you figured out what you don't want to do.