Owning a car increases your chance of dying in a car accident too. Owning a table saw increases your chance of losing a finger. Owning a boat increases your chance of drowning. Etc.
Do I think people should be walking around with military-grade weapons? No. Do I think people should be allowed a shotgun to hunt with or whatever? Sure. Do I think there should be background checks and all that to help make sure they’re used in a responsible manner? Hell yes. Do I wish guns had never been invented? Yes.
But come on. This guy apparently went room to room in his house and systematically murdered everyone in it. It wasn’t an accident, which is what generally drives the statistic you mentioned. Who knows what was going through his mind at the time. But I’m guessing that, while the gun probably made the act easier, the gun wasn’t the enabler nor catalyst here. Given what happened, I’m guessing he would have found another tool to use if he had no gun on hand. I’m not going to be morbid and name all the things within reach at the average house you could use to murder a 9 year old, but it’s a lot of things.