Charitable
I live near where Tom grew up, and he's given a lot of money to our community college. I think there's something called the Tom Arnold Net Center, and there's other stuff he's donated. He also gives out a scholarship every year, in which you have to write something funny, and if he picks it, you get your tuition for free.
Pretty nice stuff for him to do. Back when he and Roseanne were married I remember I saw him at a Little League game once. He has definately remembered his roots.
Does he "deserve" to be as famous as he is? Well, a lot of people in the entertainment industry seem to like him. Look at all the shows he's appeared on!
I think it is because while he'll never be known as the most funny guy who ever lived, he does have a down-to-earth humor that most of us can relate to.
http://www.aacc.nche.edu/Content/NavigationMenu/AboutAACC/Awards/AlumniAward/2003_Recipients/Arnold.htm
Making it at all in Hollywood after coming from such a small town is amazing - Good for Tom, and thanks to him for supporting IHCC :)