[mleonhard]

The winner of the bet does not profit personally, so it's not really a bet. They use the term "bet" because it's easy for people to understand. And it makes it more interesting than alternatives like "prediction & rebuttal".

Long Bets and the Long Now Foundation try to get people thinking about the future so we can make it better.

[kk_cz]

Even if it is just used as a figure of speech: "I bet that millions will die in next 4 years" crosses the line for me. But I guess it's just me.