yea, suicide is generally a thing dealing with mental issues. A while back, I had a friend with a biochemical imbalance, and she tried to kill herself with a razor. She wasn't even a loner. She has plenty of friends that care for her. She told us after she was treated that it was so scary watching herself just cut her wrists, but once she started, she couldn't stop.
I've dealt with similar things, and it's not always a biochemical imbalance. It can deal with like stress building up over a huge amount of time and stuff like that. I've never actually tried to kill myself, but I went through a few years where I'd write the scariest things like about how I'd kill myself. I knew exactly how I would have done it, I'd even go down and play with the knives, and cut my fingers to make sure they were still sharp. Don't give me that shit about how it's selfish, and the fools way out. You have no idea how scary it is, and you can't really stop yourself.
I'm sure there are some people who have killed themselves, and it almost seems selfish to their family and friends cause they just don't know what that person was going through.