This is an excellent thread, thanks for sharing!
I've fantasized about a spectacular suicide since being young. More of a fantasy than a plan, truly.
My reasons are the pain I would cause to my parents (I've thought maybe of doing it once they've passed, but by then, what's the point in doing it?
The other main reason is my two cats. I would leave and they'd never understand what happened to me, or why I'm not around anymore.
The final reason is... if there's no parents and no cats, then what's stopping me from becoming a park ranger or a fire lookout?