I know this feeling from my early days training. I don't think it was a coincidence that I had this issue in my personal life away from parkour at the same time.
When I finally realized that no matter what I do, parkour or otherwise, there will be people who love it and people who hate it. People who are going to judge/talk crap will find SOMETHING about you to rag on. If they don't give you crap about parkour, they will give you crap about something else, like your clothes or taste in music.
It's a losing battle to try and please people, or even to stay out of their way. Do your thing cause you love it.
Worst case, earphones in, eyes on the obstacles in front of you ;-)