What should I, as the son of a father who sells alcohol and rejects advice, do?

Selling alcohol is a major sin, and you did well by advising your father on this matter; it is your duty towards him. However, the advice should be given gently, kindly, and wisely. If he does not respond, you should supplicate for him frequently, honor him, treat him with kindness, and obey him in what is good, even if he were a polytheist, as Allah says: "And We have enjoined upon man goodness to his parents. But if they endeavor to make you associate with Me that of which you have no knowledge, then do not obey them." (Al-Ankabut: 8). There is no harm in seeking the help of some righteous and good people to advise him. As for eating from his wealth, that requires further detail.