Yeah, why is this a question?
This is so, so wrong that I don't even blame Penny and Horace and Irene. They are ridiculous jerks, but this has been going on so long and so blatently that I blame Patty.
If you are going to be a complete and utter doormat, you can always find people that will treat you like a complete and utter doormat. It sucks when it's your family, but after the first time (or at least the third time) Patty is just putting herself into this situation willingly.
(Unless there is some backstory like Horace then takes the car to deliver food to orphans and then spends his spare time massaging Patty's 47 arthritic cats so they can live a life of comfort)