What is a bet that most people take with the intention of losing it?
More specifically than TacoV's answer, maybe it's
life insurance. This could be seen as gambling on your own life, which you always lose in the end (hence intention of losing?) but want to keep as long as possible (which could be seen as losing the 'bet' since you're losing money that way).
This specific answer is good because
not any kind of insurance will do: you might either want to get the money or keep the item you're insuring if it's less valuable than your life, depending on context and circumstances.
Probably not the intended answer, but:
Shorting a stock is when you "bet" that the stock will decline in value.