I do it because i like chaos in my life (as crazy as that sounds) and between balancing work/friends/family/fun with filming/planning/editing my life is chaotically peaceful.
I do it because i like challenges. Whether it's learning to film/edit/get used to seeing myself on camera, adapt to new youtube features, trying to hit my YT goals, or setting up big projects, there are plenty of new challenges.
I do it because it helps me to meet new people. Making youtube videos is not only a great conversation starter it's a great way to meet people. I love inviting people over to come be in the next videos and i always love when new people show up. I love when people come up to me and say "this is the guy that made that video that i showed you". I also have met many great people online talking on forums like this and through getting to know my subscribers.
Lastly, I do it because it's fun and it gives me something to do. Some people enjoy coming home and watching tv, but i like coming home and getting to work building things for my next video or staying up late editing and bringing the videos to life.