I'm literally confused how a 3300 cp person could even hurt a boss at that high let alone kill it.  

 

Could someone help me understand how this is possible to kill a boss that would require an insane ammount of cp way higher than his to kill?

apparently a hacker or something else

Nope, that is totally normal, in Heidel someone beat Uraka on Difficulty 99 a long time ago, Uraka is arguably the easiest boss to 'troll', it simply takes hours to beat it one time at a really high difficulty, and a few select people apparently enjoy challenges like this.

ah ok, thanks for the input :)

Any of these people stream?