Floyd was caught, properly caught, doping during the tour that he 'won'. His reputation is now dirt. He is pond scum. He now cannot make money from cycling, has no fame as a cyclist, and now seems to spout random stuff to grab a little fame every now and then.
How do you know the other guys are definitely doping? All of them?
How come Federer and Nadal win pretty much everything in tennis? They are the best at the game, and they surround themselves with the best.
I'm not saying Lance is 100% clean, it's just too hard to know. But to understand even a little about the tour is to know the following:
a. Lance geared his entire year around the tour. He effectively ignored the tour of spain and italy. This is like Federer never playing the Australian or the French (or playing them, in his grass-court shoes and with his grass-court tactics, just for training), and focusing the whole year on Wimbledon.
b. Lance assembled the best team money could buy. Cycling tours, for better or for worse, are team sports. I don't get why people find that abhorrent, it's just a fact. So many team sports are about buying the right players.
c. Lance was appropriately genetically gifted as an endurance cyclist - ridiculous aerobic capacity.
So you take one of the very best riders with amazing genetics, you give them the very best team every year, and they focus entirely on one race.
Not surprising he won some.