Gambling on losing teams is a legitimate strategy, but more than betting on losing teams I think it is evaluating the risk/reward scenario with a specific bet. Sure, there might be a team that is likely to win, but maybe it pays a penny to the dollar. Basically, winning that bet doesn’t make a difference. I get more entertainment out of betting longshots and making sure the reward is worth the risk.
Betting on underdogs is almost always better than betting on heavy favorites, but most punters prefer betting on favorites even if the odds are low since they get tempted by the higher winning chances after factoring in the vig.
For example, some whale bet more than a million bucks on odds less than 1.01 and lost it all. Higher winning chances don't always translate to favourable results basically.