they aren't domestic animals. although they are ridiculously cute and funny to have around (i assume) they really aren't cut out for living in some concrete suburban neighborhood. they carry some legitimately dangerous diseases that they can easily pass to humans, and vice versa. also, when they reach maturity, the become pretty aggressive, and the lack of mating potential can make that situation worse. keeping one in a house is also pretty cruel to the monkey, many of which develop depression because, again, they're just not cut out for domestic life. a shitload of owners also decide they can't care for them and give them up, which causes more serious problems, as zoos usually won't adopt former pets, because they're so messed up by their early lives, and can't find places to live.
everything would be better if everyone wasnt a complete pussy.