That is not a fact, that is an opinion -- and so far as I can tell, an opinion not based on evidence before us (other than anecdotal).
The tour tests large numbers of riders, and only a few are found to be doping, and they are thrown out. Anybody beating Lance would get tested because they test all winners.
In fact, given the extreme testing of the TDF, if I were a cyclist who wanted to keep clean, the TDF is the one race I would take on. Which is what Lance has done.
Note that if every rider is doped (and your "hundreds of dopers" means all of them, since there are only hundreds of riders in the tour), then his acheivement still means he's beating everybody else on a level ground.
Which doesn't refute your argument, but sure refutes the only real "evidence" for his doping, the argument that since he's older than a lot of the other riders, the only way he could beat them is if he doped. If they are doping, his doping wouldn't help him be better than they are, just level the playing field.
So whether you believe based on actual facts and tangible evidence that there is almost no doping among the leaders of the TDF, OR we accept your opinion that pretty much every single rider in the TDF is doped, Lance's acheivements are equally remarkable.