Well the question of "rich" is actually a question today. Look at what his business was valued at when the magazine was strong and he had co-branded some casino/resort properties. There was a time when he had a real pile of money from Playboy. But not anytime lately. I think that's the interesting story. The guy lived to be 91 and he outlived the success of his business. The deal that sold the Playboy Mansion included a life estate for him, an estate restriction on the new owners that allowed Hefner to live there as long as he wanted. That kind of arrangement is sometimes made in family estate planning to preserve homestead and allow granny to live there, etc., but not common in the situation Hefner was in. I think he may not have had very much money at the end. Look at the situation with Jann Wenner and Rolling Stone - it is going for almost nothing. Roll back to 2005 and Wenner could have sold his interest and cleared $500M.
I look at Vanity Fair and the departure of Graydon Carter and see the desperate stuff like The Hive ("Where Wall Street, Washington and Silicon Valley Meet") and get the impression that being a publisher today is like being a retail chain in the cross hairs of Amazon. Not so good.
I'm thinking that Playboy was not worth so much at the time HH expired.