Mid 30s here, went back to uni 6 months ago after realising that none of the stuff I've done until this point was in any way fulfilling or meaningful to me. If all goes well, I'll be starting my career in this field by the time I'm 40.
Going back in my head and thinking "if only I'd done this after high school, or in my mid 20s when I switched fields for the first time", but I didn't and, to be honest, I don't think I could've done it back then. Part of there reason I'm doing this now is having the experience of working in other fields and feeling completely empty. My previous experiences have allowed me to understand what I don't want, what matters to me and what doesn't, what I find meaningful versus what feels void and meaningless. I have classmates in their early 20s and I can see that their perspective is so incredibly different to mine. I'm not saying I'm smarter than them or anything like that, mind you, but it's undeniable that the 15 or so years of additional experience can be rather advantageous, especially in this field I'm in now.
That's how I press on. I sometimes feel like shit, a failure who didn't follow the "successful" path I was "supposed to" follow, and a loser who took until his mid 30s to figure out what the hell he wants to do with his life. But I don't think it could've happened any other way. And all that stuff about being a "loser" or a "failure" is just me repeating the nonsense I was taught, it is in no way a true reflection of who I am or what I'm doing. If anything, I'd say that having the opportunity to start again and spend my time on something that actually has meaning to me is quite a lucky position to be in. It hasn't been a smooth road, and I don't expect it to be any smoother in the future, but it's something I've chosen.