No No No No No No No No.

If your parents find out you have money, they are going to try their hardest to get every dollar possible from you.

Never tell them.

It feels like I'm being ungrateful and selfish when I think of all the good things they've done for me and now that I have the means, I'm hesitating to help them. What would you do if you were in my shoes?

Dude, you would not be "helping" them. You would be making things worse for them. They will spend every minute of every day thinking about all that money you have and thinking about ways to spend it. It will do them absolutely NO GOOD to tell them about your money. Let your parents handle their own finances. Let your parents handle their own debts.

If you want to do something nice for them, do something SMALL like a $5,000 vacation or something. DO NOT DO ANYTHING that will make them suspect you have huge sums of money.

Money changes people. Money rips apart families. Money can turn decent people into despicable people. Money is like Sauron's ring. In the wise words of Gandalf: keep it secret, keep it safe.