I'll state something else. A contrary idea. I don't know the answer. But I believe it is a valid question to ask.

Is it possible the Navy selection process for SEALS overlooks mental fitness outside of their physical/mental endurance?

Is it possible that the psychotherapy is very poor, and over abundance of certain medications such as Ambien a sleep medication that fucks up a person, among many others. Wrong dosing,etc.

Is it possible that there if these are all suicides, to look historically as far back at Gallen a famous Roman soldiers physician who exclaimed with worry about what became in the beginning of the modern era, "shell shock"?