Because it is. Over the past couple of years a few people I know (some better than others & none I'd consider a friend) have killed themselves, one of whom had several children. Was that person thinking about the effect their self harm would have on those children? No, not at all, ergo selfish. Another killed themselves with their dog for company...who was going to feed the dog? And what about the people who find the body? Selfish, thoughtless and cruel. Nor do they consider the effect their act has on the wider community, I didn't know the girl who threw herself off Marine Drive but I think about her every time I walk past the hippy memorial that's up there (which is quite frequently because it's on my parish training route) it's terribly saddening.
Stupid is obvious, if you kill yourself then you will be dead and that's a really stupid thing to make yourself. But I was talking about Keith Flint's, his suicide was stupid and reckless because he was influential (for some).