But I don't regret it. Those years are the foundation of the career I have in my 30's.
Back in those days, when I wasn't at a computer, I was listening to non-fiction audiobooks on business and software. I don't know how I had such motivation bvack then, but I'm glad I capitalized on it while I had it.
In other words, to people reading questioning if they're working too much: it's okay to work hard as long as you're doing it for the right reasons. (I'll purposely leave "right reasons" undefined, that's on you to evaluate)
I'm just generally not a fan of people putting other people down for wanting to be productive. It's okay to work hard, and it's okay if your identity is your work at least for a short time in your life.