I knew the pilot, as his (previous) office and my office are in the same hangar.
Incredibly nice guy. Very, very sorry to hear about this.
I don't want to speculate on what happened. However, I do have a general thought that is shared by many of us who knew him. Please do not misinterpret this, as he was a very competent guy.
The very low pay and utter lack of benefits of many of these "high end" corporate pilot positions, leads to the necessity of post retirement jobs, flying junk for peanuts.
In some ways, we in the corporate world simply "eat our own" so to speak, as we accept these abusive conditions. If we don't, there has always been someone who will.
I'm not going to name names, but when I see these career pilots living in low income housing, and dying broke, I know they are getting screwed intentionally.