Reasons
So now that we know what happened the next phase is to find out why...
People must be pretty desperate to take 149 people with them. It could be terrorism but he didn't say anything,so no religious or political screams prior to a martyr death. Keeping silent means a missed unique terror opportunity.
This therefore sounds like extreme depression of a 24 year old leading to a suicide unable to think of consequences for others.
I hope for the aviation industry his reasoning was not around the current financial woes of young pilots who have invested the value of a house to get a job which in many cases now only pays a mediocre salary.