Nothing would change for me. I've never been afraid to not show up for a raid because I wanted to hang with my friends. I've never decided to not take a job or not take courses at school because of raid times. What I've done every time is simply quit raiding or went more casual with it. WoW is a hobby, and if I didn't play it for the last 8 years I would have probably been playing something else. Maybe Magic: The Gathering, maybe Xbox / PlayStation games, etc. I also wouldn't have met my best friend if I hadn't started playing WoW. That would be depressing since he is one of the greatest and most supportive people that I know of in this world.
In the end, life is made up of the things you do and the decisions you make and any little change could potentially have massive effects on your whole life. Ever heard of the Butterfly Effect? In that changing one small thing in the past would change your whole future? That's what happens when you start regretting the way you've spent your time in WoW and the other things you could have done. You can't for sure say that your whole life would be better. Sure maybe you take that job that you really wanted, but maybe you hate the job and end up doing something you regret and get fired and can't find work for three years afterwards, forcing you to crash on your mom's couch and slip into a drug habit. Not that it's the most probable scenario, but you just never know what could have happened.
The only thing I'd tell myself if I went back in time would be to roll a healer from the very start and join a hardcore raiding guild during BC. It took me seven years to find a guild that is actually on the frontlines of raiding, and I regret the time I wasted before that in all my other achieve-nothing guilds.