Because children are unable to escape cyber-bullying the only choice they feel they have is to end their life.
Paedlophiles ask young girls to meet up with them or send them pornographic or nude images and they do so; the girls also do so with boys their own age in order to fit in.
Parents are not keeping a close enough watch on their children in order to monitor what is going on on their page. For example posts are only on snapchat for 24 hours and once the person posting it has deleted it, the person receiving it has no evidence to say that they are being bullied or abused in any way. Even when their is clear evidence that their is something going on (for example facebook and googleplus) children don't always bring it to an adults attention.
It should either be monitored properly by parents and teachers and explained to the children how it should be treated responsibly otherwise, not used at all.