It is very simple. He doped. He lied. He personally hurt people to protect his lies. He finally told the truth.
Lance Armstrong has now joined the ranks of Pete Rose, OJ Simpson, Tiger Woods, Roger Clemens and many other sport celebrities whose personal failures (yes, choosing to use performance enhancing drugs is a personal decision) out-weigh their sporting achievements.
Lance Armstrong is someone who should not, today or ever, be held up as a model for anything other than a perfect case study of how far someone will go to protect their reputation and win at virtually any cost.
What about his foundation, Livestrong, improving the lives of millions of cancer survivors and family members? Does this (as has been stated by many people in the sporting world) hold up his moral character to a certain degree? In my opinion, no. He is not making a personal decision every day to improve people's lives. His foundation does. It is their mission and the people working for the foundation care deeply about it. He invested years making personal decisions to dope, lie about it, hurt others to protect his lie and stand behind that lie for as long as he could.
The lesson here is simple, as well. Leaders must protect people's trust above all else. Without it, nothing else really works.
Lance Armstrong is, and forever will be, a leader. He has and will continue to influence millions of people through his cycling fame, cancer struggles and foundation work. However, he chose to make personal decisions that undermined his credibility, integrity, moral standing, and trust with everyone he will associate with for the rest of his life.
Was he in a high-pressure, high-stakes world in elite cycling? Yes.
Did he think doping was justified because it was common place in competitive cycling? Yes.
Was his stature in the cycling world and the humanitarian world going to crumble if he told the truth? Yes.
Will his position, influence, power and abilities as a leader ever have strength and merit again? Sadly, no.