I haven't been cyberbullied, and if I have, it was years ago when the Internet was still navigated via command line and "Hot or Not" was considered new. It was also during a time when the term "cyberbully" hadn't been invented or used. And any recent cyberbullying attempts were conducted by trolls on Wookieepedia, and I usually just ban them. I've even range-banned them. Their nonsense was then deleted and my final message to them was a bit on the snarky side, but still infuriatingly polite, just to hammer it home that I feel that they're not worth my time. Nor are they on the same level of sentience.
Now, bullying in general is indeed a problem, and it can be devastating to its victims. I was bullied all throughout school, both elementary and high school. There was a bit of bullying in college, but my classmates and the faculty and I teamed up and took care of that quickly. The most recent bullying I've dealt with was when I was living in Windsor, and a group of teenage boys were giving me trouble; to the point where I was involved in a vehicular assault (that's how I broke my foot). Moving was the best solution for that. Now, those boys are giving my brother's wife trouble. We're waiting for them to give lip to the wrong person and have their faces caved in, or be shanked as a result.
The reason why people have taken their lives is because if the harassment is severe and persistent enough, it strips away your defenses and you run out of options to cope with it. You're called "stupid" (or other nasty things) so often that you believe it, you have no support system whatsoever, your coping skills are meager and are not working, and no matter what you do, those idiots are there, tormenting you. It eats away at you and your self-esteem. You've run yourself ragged because your fight-or-flight reaction is constantly on. You become paranoid, you wonder if anyone really, truly cares about you, because every single day, you see that people hate your guts, beat you up, take your things, and call you nasty names and spread horrible lies that everyone believes, and no matter how hard you try, you can't fix it. Any attempts to stand up for yourself are met with immediate ridicule. This goes on day in and day out, week after week, every month, every year. The same damn thing over and over and over.
Finally, you can't take it anymore, and you snap. Depending on how your brain is wired, you may act out aggressively, or you may hold it all inside. If you bottle it up, it consumes you. Eventually, you can't take the pain anymore and you simply want it to end. No one has helped you, no one has come to your aid, no one has even tried to save you. To you, no one gives two shits. And that becomes the primary reason for attempting suicide: Because no one cares.