I'm going to sleep through thanksgiving dinner and order a pizza after thanksgiving dinner
That's a little odd. Will doing this make you happier?
I will be happier. I'm fed up with hosting thanksgiving dinner every year.
If the holiday isn't important to you, then it's fine for you to avoid it.  There's nothing wrong with avoiding things that aren't important to you.  Enjoy that pizza!
But I don't want to feel like a jerk to my family.
I understand that the holiday may be very important for them and not you, but how about just trying to make a compromise with them? Why not just telling them your situation, and just showing up for a couple hours and then doing what you wanted to?