He/she was full of shit by calling himself/herself an
underdog, but knew that he/she could gain an advantage on an opposing person/team by calling himself/herself an underdog (and end up facing less adversity by doing so while placing more adversity on the opponent,
throwing the game/race, a way to get support from people who would not otherwise support them), or claiming that he/she had lower odds overall. Really, since he/she was
playing all sides, he/she could always end up on the side that triumphed, as long as people allowed it.