Those suicides would have occurred using other means if a firearm wasn’t available. Seriously, if somebody is going to kill themselves, they are going to do it however they can. Self-drowning, trains, semis, asphyxiation via bag on head, self-exsanguination including death by a thousand cuts method, CO poisoning, pills, “hotshots,” poison, “Death of a Salesman” style vehicle “accidents,” along with combination platters of methods. The ones that involve other people directly are particularly nasty, because they can leave the other person with a sense of guilt, and, depending on the exact nature of what happened, may require far more than a mop and bucket to clean up after.
In many respects, suicide by gunshot, depending on where it is, is a far more humane thing than many of the other options. Having heard descriptions of what it sounds like when people have slit their own throats, it cannot be a pleasant experience, especially since they have time to feel the pain and think about the fact that, no matter what they do after that, they’re dead.