You go to a bank to manufacture you a derivative on eg the stock market. The deal is that you pay them 30 million dollars now, and in 30 days they either pay you x dollars with probability p or you lose everything.

Eg they pay you 100 million dollars, if the S&P 500 index goes above, say, 5000 which they think will happen with probability of just under 30%.

If you do the math: the deal is fair.

If you lose the bet, you get your inheritance.

If you win the bet, you get your 100 million dollars from the bank, and presumably pay the 30 million dollars back (if that's a stipulation in the will).