Because we wanted to.
We wanted to believe local-boy-makes-good and American drive triumphs and sheer willpower overcomes setbacks and propels someone to win a gruelling event seven times in a row, with no rule breaking and no collusion and no lies.
What dupes we were.
We believed Lance for so long because he did - he believed himself. He believed in himself and his goals so completely that he could, apparently, lie convincingly and appealingly. He was strong and attractive and charismatic, and he was driven, and he was a hard worker and he was a phenomenal competitor. And very smart.
He was also, it seems, a liar and a cheater. Never mind who got hurt along the way.
And we swallowed it, hook, line, and sinker.
It's a cautionary tale. In a lot of ways. For a lot of us.