Gambling is of course the best way to launder money. I think the guy’s millions really came from criminal activity, not “investments.”
Based on what we know about his work history, I think your theory is valid. A three-year stint at Lockheed back in the 80s. No record of him passing the CPA exam, or having his own accountancy practice. And so far, no record of him working as an accountant for other companies or organizations. In fact, the shooter seems to have been out of the workforce for the better part of 30 years, but still amassed a small fortune, enough to acquire multiple properties and two aircraft.
Another FReeper suggested Paddock may have used his planes (and skills as a pilot) to fly drugs into the country. Under that scenario, your theory about Paddock using gambling to launder the money makes perfect sense.
As this saga unfolds, I believe we’ll discover that Stephen Paddock was involved in all sorts of activities that will stun many Americans. And apparently, he flew completely beneath the radar (no pun intended) until he opened fire from his perch in the Mandalay Bay.