Here's my thing about hobbies: rarely are they some sort of moral imperative or judgement on a person, save for ones violating the rights of others and mean fan fiction doesn't count.
Often times I feel regret over dumb decisions in my hobbies as a young man. Fan fiction, RPGs, costuming, films, prop making, I've done much of it and often think to myself,"that was a waste of time."
Ironically, I would now say that living a life of regret is a waste of time. Looking back and bemoaning choices does nothing for you. You can't go back, you won't land the dream girl, dream guy, dream job, dream life by looking backwards. That's an impossibility.
All you can do is learn from it, build off of it and recognize important knowledge gained through it. Often times, the knowledge I'm kicking myself for not knowing I wouldn't have known without some painful experiences.
All you can do is move forward.
I had to learn most of this very recently, through an extremely painful relationship decision. A woman I had loved more than 20 years ago had essentially kicked me to the emotional curb in 2006, with no explanation or reason. For a long time after that, my severely obsessive side kept me locked into a desperate cycle of grief and self-hatred, wanting answers but not knowing how to find them. Years passed, and I thought I'd reached a point where none of that mattered anymore. Then about 2 months ago, we started chatting again online, and for a short time things seemed to be going okay. But it soon became very apparent to me that her emotional walls were still up, and I panicked all over again. I'm not proud of my behavior, but we both wound up saying things we shouldn't have, and at a certain point I cornered her with, "Tell me this flat out - do you still love me or not?" She took it as a personal attack instead, defiantly invoking the memory of my dearly departed mother, and even accused me of being an emotional abuser. That was my breaking point; I'd asked her for a respect-driven "mercy kill" shortly before, and when she refused I decided the only way out was to do it myself. I hated making that choice, because I remembered the tremendously loving and selfless woman she once had been...but being constantly shoved away had drained me completely. At first, I felt horrible about the entire situation, but I then experienced something which truly surprised me in a very good way - the realization I was no longer leaving in fear. That one change has given me so much inner peace, and I am immensely grateful for it. I will always remember her as she was, and I'm able now to have peace without requiring her to be the source of it.