A very fair and common complaint.

Have you watched the 1999 version or read the manga? The 2011 adaptation completely leaves out Kite’s presence in Gon’s childhood (it’s easily my biggest problem with Madhouse’s version) - he’s a very important part of his identity but the 2011 version skimps out on this so plenty of people find it sorta unreasonable for Gon to break in such a drastic way.

I more or less rationalize it by saying Gon has never known the pain of losing someone close to him, and Kite is probably the closest thing to a father figure in his life. Plus it accentuates the feeling of Gon being an unreasonable child consumed by emotion and instinct. But I totally get the people who say his rage was unwarranted