It's amazing had the double diffuser farce never have happened Vettel would be a triple WDC now, at only 24. Note that the only other two to have won 3 times back to back are Schumacher and Fangio. Senna could've done it too, in fact could be the only one alongisde Fangio to do it 4 times back to back had he not been unlucky in '89. Vettel could still get a triple though, at only 25
When I look back I see he's being given a lot less credit than he deserves.
(ok, schumi did it 5 times in a row so the 4 doesn't count