Bullying in clubs of artists, in art clubs and at exhibitions, very bad bullying,

I am a member of 4 clubs, including an art-club (amateur painter) I paint myself pictures (in acrylic) and sometimes put my pictures out to expose. What I would be interested in: do you (possibly also artists / hobby artists / club members) also have the impression that in the clubs they make a very nasty ,very bad bullying ?
There are several examples. I presented an image on an easel at an exhibition. Promptly image and easel was pushed into the corner, by "UNKNOWN". Another time, a decent blob of jam was on one of my pictures! And these were not kids who did that. : Mad: : Mad: : Mad:
When someone asked for me to buy a picture, a person I know, said to someone who was interested, he is selling his pictures because he has debts. Which is a lie, of course.

The list of bullying is long, but enough of it! Why are artists just such bullying persons? In the other clubs, there are also problems, but not permanently and with such trickery!
Artists should be senisible and less aggressive persons. So what ? : Confused: