I don't have hard statistics, but there's a New Yorker article about survivors of Golden Gate Bridge suicide attempts that says many of them regret the attempt and don't try again. The people who survive jumping off a bridge is probably pretty close to a random sample.
What's your point? The post you replied to is just saying "of people that survive, most wish they wouldn't have tried it." If the sample is indeed random, that means most who didn't survive would feel the same way.