Probably swimming in debt.
He was worth 15 million and had a thriving business. Unless he was in debt much more than 15 million, but I doubt it.
I suspect that he may have had other issues that never came to light. Some are saying he may have been diagnosed with a terminal illness.
Robin Williams committed suicide because he was recently diagnosed with Lewy Body Dementia and started to feel its affects.
I forgot who, but another famous person committed suicide because they were never able to heal from the wounds of being sexually abused as a child.
Often, when people commit suicide over money, its usually related to other factors such as divorce, not seeing your kids, failed marriage or relationships, i,e., suicide is usually the result of many factors, not just one isolated variable. Mirra seemed to have all of this, based on what people are saying.
It will probably always remain a mystery.