There's no good reason to have an automatic weapon unless you're expecting an invasion lol.
But guns are a hobby to a lot of people. 99.9999% of people who own those sorts of guns just like to take them to the range and play with them. They're gun geeks. I'm a geek when it comes to my bicycle or fishing and other people like to mess with guns.
But as is always the case, the idiots ruin it for everybody. The people who can't keep from texting while driving cause you to get a ticket if a cop catches you with a hand on your cellphone while driving. The Vegas shooter will make it harder or impossible for gun owners to get bump stocks.
Will it change anything or prevent the next mass shooting? No. But government must 'do something' even if it's next to meaningless.