Why is my dad this way?

My dad can be a nice person. When I was young my dad took us everywhere, he spent a lot of time with us, But there's another side... my dad has anger issues. Me and parents would get into argument and I remember one time he got upset and punch a hole in the wall. That was a very scary time. Me, my mom, and my sister was scared to ask my dad for anything because you never knew what you was going to get. Even if we asked for money he be very upset. Onetime we was at a grocery store and my mom didn't have enough on her... my mom asked for money and he threw the money at the cashier (the lady). When my mom would treat him to football games or do anything special he would complain. My grandfather (his dad) was on his death bed and my mom was calling him to let him know... he got mad at her cussed her out and told her that she is messing up his money.(He had a job in another state). Same with his best friend... he didn't care he just continue on the conference call. Moving on to now my parents are now separated and he so focused on this home based business. He stoled money from my mother, that's one reason why they are separated. Money is his life. He gets very upset if we don't want to join his business. When I moved to New York he never called to check on me I always checked on him. The only time he called if it's about the business or money. One time the conversation was like this," Well I'm going to send you a link to sign up for the business and we can talk more." If we don't join the business he doesn't want to have that relationship. He also likes drama... even when my sister's are upset with each other. Sometimes when I visit him he gives me a half way hi and than get excited to see my daughter. He has 6 grandchildren and he shows favoritism to the last two. What can I do to fix our relationship?

Why is my dad this way?
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