I'm going to tell my father not to purchase scratch-offs/lotto tickets
Why shouldn't your father buy lotto tickets?
They are a waste of time and money.
You're right to be concerned if he's spending all his money on lottery tickets. The odds of winning are worse than Las Vegas, but if he's just playing a few dollars a week, it sounds pretty harmless. In that case I wouldn't intervene.
He's spending all his money on lottery. I wouldn't be able to handle myself.
I understand, then I think talking to him and trying to get him to stop is good. Research some information on gambling addiction to further help him.