He thought, still thinks, that the word 'cheat' did not apply to him, since 'cheat' means to gain an advantage over someone by what you do and , for him, doping was like putting air in the tyres or having water in the water bottle. By his logic, he obtained 'a level playing field' (as he put it). That's a somewhat restricted confession! Lots of others were doing it, it was as regular as inflating tyres , so he did it.
He might have explained why he didn't seek to stop the others cheating and report what he knew. No, he sued the Sunday Times for suggesting that he cheated, made great efforts to ensure that his cheating continued unreported, and , by inference, that the widespread, 'like air in the tyres' cheating continued too.