First of all, gun laws are strict, you go through strict background checks, and other stuff to obtain one
And there is a purpose to obtain Assault rifles, since you probably dont know American history, let me tell you why the 2nd ammendment exists, if a tyrannical government is to rule, the 2nd ammendment was a way that the citizens would be their own militia to take down such government, and this was with having in mind for people to own canons. Now with assault rifles its clearly not necessary to own one, but I really dont see the issue, people are gonna get a gun anyway