I think he played that game very well - openning with HT to get a quick Mountebank, 2 early Mountebanks, then Village, because he needs some actions, and then Village/Smithy idea to play the Mountebank more often and also to trash Coppers and Curses in one big Forge turn (not to mention 2 Villages to a Province in the endgame).
You OTOH played a dumb (sorry, but it's true) BM-Mountebank strategy (with Forge as a bonus).
I don't know which one of you has better chances (maybe Geronimoo would be able to answer), but your opponent played an interesting strategy and you played a noninteresting BM. So you should be happy that the BM lost
And about the luck - he had 5 Villages yet look at turn 17 - He has 3 terminals and isn't even able to at least Forge something into Province or Gold!
PS: I personally think that Colony/Platinum adds more luck to the game, but I never thought about this deeply, so it is just an opinion, nothing more...