This isn't the first time that somebody on Cowell's shows have attempted to kill themselves (or indeed, actually killed themselves!). BGT (and the X Factor etc) are set up in such a way to build confidence and then smash it. As viewers, we are watching it thinking, "omg, how can they think they are good?!?!"...
http://www.dailymail.co.uk/tvshowbiz...ht-family.html
The reality is that because they even go to the judges, they have 2 audition phases before that, both times in front of producers and they are told over and over again how fantastic they are and then their dreams are destroyed.
I'm actually surprised this isn't a more... common occurrence, if I'm honest. Especially since sometimes, these "bad" people are put through to the live shows on the premise that they are told over and over they are really good, only to be told they were terribly awful, live on TV...