Suicide is a person's right? You are stretching things quite a bit here to protect guns. So it is cool if it is an accident with easy access or that the person would not be dead if they did not have a gun.
Cars are also a bad example in general. Cars are highly regulated things. The government requires numerous safety features, licensing and registrations of such things. Given the number of cars out there the percentage is probably low (I may be mistaken on the percentage though).
Suicide is obviously a bad thing, and I do think that people who want to kill themselves should be discouraged from doing so or attempting so in most circumstances. Sometimes there are viable alternatives to ending someone's pain that don't involve suicide, sometimes there are not. But suicide is not a crime, and they don't charge or prosecute you for suicide (Especially if you're dead.) or suicide attempts. So, yes, it's not good, but it's not a crime.
Also, I'm not protecting guns. I don't really care for guns, but clearly a lot of people can handle them just fine (Like alcohol.) and they do serve many other uses aside from violent ones.