I could give you the same good reasons other posters have, but I would add, they are just so darn fun to shoot. They just "dance in your hand"
The Second Amendment is a doomsday provision, one designed for those exceptionally rare circumstances where all other rights have failed -- where the government refuses to stand for reelection and silences those who protest; where courts have lost the courage to oppose, or can find no one to enforce their decrees. However improbable these contingencies may seem today, facing them unprepared is a mistake a free people get to make only once." -- Justice Alex Kozinski, US 9th Circuit Court, 2003