Simple.
America has many times more guns floating around than are necessary that are way too easy to get ahold of by anyone who wants one, whether for lawful purposes or otherwise. The gun industry over the years has come to see the huge profits they can make marketing their product just like any other consumer product and so they pump them out of their factories around the clock day in and day out. The guns go to dealers then get sold to legitimate buyers or stolen from the dealers during break ins, or they get stolen out of people's homes and cars during burglaries then sold on the street.
All the while, the NRA lobbies (bribes) GOP lawmakers to block any and all common sense restrictions on the availability and supply by hiding behind the 2nd Amendment. All just to keep conservative white males with manhood issues happy and feeling safe and secure knowing their surrogate penises won't be going away anytime soon.
And people keep on getting shot and dying or spending the rest of their lives maimed and crippled.
You think only white males own guns? Lulz....nutter