You know, no one is a Tour de France winner until they are a Tour de France winner. A lot of cyclists are better at, say, age 27 than they were at age 25. For a variety of reasons.
Or perhaps the conspiracy theory is actually true: that somehow one guy had substances that no one else did or had a doctor who knew something no other doctors knew and yet sold such knowledge to only one cyclist, no one has ever admitted to seeing this cyclist use anything illegal, he managed to use all those years without officially testing positive, and that's why he was better than everyone else.
It seems much more likely that he put into his body (or not) the same stuff everyone else did (or didn't) and that the differences were in training, team, drive, body, whatever.
Or perhaps the conspiracy theory is actually true: that somehow one guy had substances that no one else did or had a doctor who knew something no other doctors knew and yet sold such knowledge to only one cyclist, no one has ever admitted to seeing this cyclist use anything illegal, he managed to use all those years without officially testing positive, and that's why he was better than everyone else.
It seems much more likely that he put into his body (or not) the same stuff everyone else did (or didn't) and that the differences were in training, team, drive, body, whatever.