To get the finer things in life, they appropriate them from people who have earned them. After all, it's not fair that they have so much while the poor, downtrodden, shiftless lowlife has so little. Since people are generally reluctant to give up things they've gained so dearly, the thieves need to use force. Being relatively inarticulate in matters of economic dialectic, they need a visual aid to convince their victims of their moral rectitude. They need a gun.
Righteous people conform.
If they are required to register before they can buy a firearm, they do. If they have to fill out forms, they do. If they're not supposed to park in the handicapped spot, they don't. They'll sit at a broken stoplight at 3 in the morning because their conscience is stronger than their ego. Members of the shadow class make their own rules.