You touched on a key point in your long long list of reasons.
Destruction of marriage.
Studies have shown that many if not all of these shooters come from broken homes. They come from a home with an absent father. If we fix that, we will almost end mass murders overnight.
Almost all of societies ills are traceable to unmarried, absent fathers, it’s a common denominator.
ALL of the males that have done mass shootings have been on Ritalin or related drugs!! Don’t know about these recent ones because they stopped REPORTING the FACTS!