I hate middle aged people so much that I openly scorn them in public, private and business settings.
Did a middle aged person do something to make you dislike them so much?
Yeah, a middle aged guy fixed my computer but did it all wrong and wanted to charge me anyway.
Being upset with that guy is fine but you shouldn't be upset at people because of their age. You problem with that middle aged guy was a one off thing and it's not going to be the same with every middle aged person. Lumping people together because of their age is going to cause you to miss out on potential great relationships in the future.
I couldn't give a fuck about relationships with middle aged people because they are all like this guy.
You are making blanket statements about a whole group of people just because of one encounter with a middle aged guy and that is misplaced. Don't allow yourself to be narrow in your thinking. Give each person their own chances with you.