Bombmaniac
I won’t analyze everything you said but this needs explanation: “like the idea that they owe you anyway so why should you thank them?”
Your parents owe you nothing. They gave you life and everything you have. There is no way to repay a parent for all they have done, carrying you 9 months in the womb, feeding you overtime you were hungry. Changed your diapers when you were dirty. Took you to the doctor when you were sick. Held your hand when you were scared and calmed your fears. Put you in school and paid for your education. There’s so many things to be thankful for. Even if your parents weren’t or aren’t the best parents, just for giving you life you have so much to be thankful to them for.