Last but not least, if you vote away my hobby/toy, don't whine like a little piggy when I rally others to vote away your hobby/toy. Government is force which should be used sparingly and responsibly.
No they haven't. This is a bizarre misrepresentation of the scale of gun violence in the US, and obviously access to guns causes gun violence.
As you've almost spotted, the problem is one of radicalisation rather than either gun ownership per se or mental health. Other countries have guns. Other countries have people with depression or PTSD. Mass shootings in other countries are generally correctly labelled as terrorism. But people are unwilling to realise that the American mass shooting problem is one of terrorism.
Is someone having political beliefs that they're willing to die/kill for a sign of mental illness?
I think you're making an assumption that this is what is happening. What do unsuccessful, captured suicide bombers say?
The second is incredibly interesting and seems very much like a brainwashing. I can see how an otherwise normal person can end up this way.
Also, second what other people are saying - I'm so sorry you were hurt for so long. I hope that you stick around a while, continuing to advocate online for the trans community.