At least, that was his story at the time.
The reality is that "Scotty" conned wealthy investors into investing in a non-existent mine. One of his investors, a Chicago millionaire, enjoyed the trips to visit Scotty and Death Valley enough to ignore the swindle and eventually pay for contruction of this extravagent home to stay at during his visits.
In keeping with his colorful character, Scotty told friends that he paid for "Scotty's Castle" with profits from his mine (and no, it's not true that the massive church organ hides the entrance to the gold mine).
