You might upset at least 1 person
Odds are, at the very least, 1 person cares about you a little bit. Even if you don’t have any friends or family, you’re probably important to someone, and if not important, maybe you bring the tiniest bit of joy to their life. If you are completely certain that no one cares about you in the slightest than this reason does not apply to you
Suicide is illegal. I think. In some places maybe? I remember hearing a stand up comedian do a joke about how suicide is illegal and saying something like “What are they going to do charge your dead body with a crime?” It may have been Jarrette Moore, and I’m sure he put it more eloquently, but yea, I believe killing yourself is illegal in some sense of the word, and it’s not good to do illegal things, so that’s a good reason not to kill yourself.
Unless you have access to some sort of euthanasia drug or are certain that you’re jumping from a high enough altitude that your body will be pulverized eminently, maybe from a plane or something, you will probably get hurt. Dying definitely is painful so the longer it takes you to do it, the more suffering you will endure. You don’t want to writhe in pain do you? Of course not! So don’t kill yourself.
Sorry I could only think of those 3 reasons, I don’t know anymore reasons why you shouldn’t kill yourself. If you can think of more reasons why you shouldn’t commit suicide, let us know in the comments! We will use that information to compile a more in-depth list in the future.