Both. Almost everyone gossips at one point or another, some don't even notice their doing it. A combination of envious and being bored would probably bring out the biggest talker. It also depends on what one is gossiping about, and it can be good and bad. Although we often hear people talk bad about others, a nice and envious individual might say something like "she has really nice shoes." Those who gossip a lot aren't always bored, but most of them are judgmental.