If I wanted to off myself I can think of far easier ways to do it and I would not deliberately take 150 people with me.
zeddb, you're thinking like rational and mentally healthy person.
Why are there cases - as happened in a country town in NSW, AU last year - where a depressed man shoots his wife and kids before shooting himself? And nobody knew until then there were any problems. Why not just shoot himself?
Why do some sad, twisted people commit "suicide by cop"?
My own cousin died by suicide. She had struggled with depression for a long time, but had recently started a new treatment that everyone thought was working because she was happier than ever. As it turned out, she was happy because she'd made a plan to end her life. She didn't think at all about the effect her death would have on her family and indeed she did it in a location where it was inevitable that it would be family that would find her body. She was convinced her action was the right thing to do and that everyone would be better off without her (she left a note), even though of course it absolutely devastated everyone. And of course, everyone in the family swore they would have done something if only they'd known, but to everyone from the outside she looked healthier than she had in years. (She herself was a MH professional.)
You just can't always know.