Because people by nature do not want to put in the time or the work to achieve happiness. They would rather steal yours or see you unhappy because misery loves company. If they spent half the time and energy trying to create their happiness or go after it instead of bringing yours down they would be twice ahead of the game
people envy what they want but do not have. or, they you what you have, and connot figure out how to get that for themselves And most people are not reeally aware of what will make them happy, and the happiness of others feels like an insult
I call that envy. It's because everyone wants to be happy and when you are miserable, having around someone who is happy makes it even harder for you because you're reminded of things you want but don't have and it makes it even more painful for you.
