He's a guy that's made a lot of enemies over the course of his career, he's the absolute king of his sport, he's very rich, and thus he's an enormous target. Sure there a lot of people who would like nothing more than to see his fall from graces
Did he take PED's? Who knows. It's quite possible he did and got away with it just as virtually everyone else did. Maybe he didn't and is just sick of being endlessly hounded about it, and figured if he just admits his enemies will be satisfied and leave him alone so he can live the rest of his life in peace. Even if he did, people act like any old average joe can pop a pill and suddenly turn into the greatest individual athlete of our time. It can be argued such drugs would give him an edge among other athletes that are nearly or as good, but who's to say they're weren't on the dope as well?
You can also argue the point that it would have been a true testament to his greatness if he didn't use PEDs even though his competition was....that he could win without drugs, and prove it.
Like F-M said put the * next to his name in the records book and leave it at that. OK the guy might be arrogant, rich, and was either lying then or lying now. Still the action being taken against him seems extreme. Everyone looks the other way in the NFL and the worst MLB offenders get an asterisk next to their name in the record books. The people after Lance want to see him completely and publicly destroyed, he must have really stepped on a lot of toes on his way to the top.