It's all about "if somebody has something I don't, I'm worse off as a result". It's the same psychology that leads to people telling a lunch lady she can't make such good food because their kids' lunch-lady-prepared food isn't as good[1], so, therefore, their kids are worse off than they would be with everybody having crappy food. People try to justify it as "we should all be equal" or some garbage.

http://www.huffingtonpost.com/2012/10/08/annika-eriksson-swe...