I'm not going to hold the door open for people
I'm confused. Was someone rude to you in the past and didn't hold the door?
Yes, now I am doing it with everybody.
It's understandable that sometimes you can't always be polite, but you should still try to hold the door for people as you want them to do the same to you. Worse, you can get someone hurt if the door slams on their face, so holding the door for someone is both the polite and the safest way to do.
Lol, you're weird. I'm not gonna do it.
No one can force you to, but again, it's a gesture of politeness and it's a good way of telling people that you care for them even with the slightest act of kindness. We need more people like this and if you act rude, then you can expect that people would act more rude to you.