From what i understood from the new last week tonight episode, they were just lucky, that the door fell off already, before they reached altitude. Otherwise all the passengers would propbably have died. I think 20 million dollars is perfectly appropriate for being subjected to hours of panicy fear of death.
And if you would put your life on the line to win 20 Million Dollars, that is your personal choice. I wouldnt.
Finally you need to consider that the 1 Billion is the start of negotiation, and the companies will aim for much lower. If they just start with idk. say 100 million, the company would try to haggle it down to 10 million.