I'm an atheist who celebrates religious festivals and I do it for the food, drink and good company. But I don't try to go out of my way to do it. ie., in a hypothetical if my Muslim friends and family are out of town, I wouldn't celebrate Eid. But if they happen to be in town I'm happy to join them.
This is what I do not understand. If you think I am delusional, why would you be happy to join me in it? I find it very strange that someone who thinks I am mentally challenged would expect a party invitation to celebrate it.