Why is it that my parents refuse to spend anything on me but still expect me to give them a luxurious life when they retire?

They charge me for food, they charge me for gas. They expect me to pull money out of the air to pay them for everything. School needs are seen as a burden and sometimes they don't even pay it so I have to sell my stuff and do side jobs to get the money for it. They don't even pay for my college tuition.

Yet they expect that the moment they retire I'll buy them a mansion and give them 100% of my salary because I owe them and its my responsibility as their child.