The hotel side is not that hard to imagine - an HH Diamond can easily be cranking 40 points per dollar on average with Points+Points, credit card, the 2x/3x promos, and a myriad of other HH promos that have been going on this year. (Some folks had stays there were cranking out a lot more, but on average, across many properties, 40 per dollar is very doable.) So...that's under $10,000 in hotel stays, assuming he doesn't use his HH Amex for other purchases.

As for the air miles, that's obviously a lot of flying - unless there is some Pudding Guy type of partner activity going on, which it doesn't sound like there is. Maybe 200k BIS, 250k in "regular" bonuses (100% elite bonus, booking, echeckin, etc.), and 150k in other promos, partner activity, credit card usage, etc.

My point is less about how Dudemon actually did it and more about how it's actually pretty doable for any road warrior who holds a couple of good elite levels in the various hotel and airline programs.