True, for most punters, all betting is a long-term losing proposition.
How are teasers & parlays different than say side bets???? Depending upon someone's money management style vs type of bet made, the odds are longer for these bets which make your per unit return negative quicker than side bets. You go broke quicker.
Of course, nothing beats the thrill of hitting that 7+ team parlay. Its like a hole in one in golf. It keeps you coming back.