The scenario in which the bet does not pay off results in 1 million people and their descendants being stuck in a terrible situation, with distance making aid or relief impossible at scale. This is something that could be mitigated by making sure that the first planet we colonize isn't some kind of unregulated fief belonging to the first person who threw enough cash at the problem of getting people to Mars.
Which is a long way of saying that I may not be one of them, but I sure as hell will feel sorry for them.
That is true, if it succeeded for a while and then failed it could produce a casualty count on the order of Gulf War 1. Not doing it could result in civilisation extinction via nuclear war or asteroid strike. I still favour doing it, but I see how reasonable people could disagree.
I believe Elon said it would take 40-100 years for the population to reach that point, and he is saying that there will be a return mechanism, and a probably an extreme labour shortage which favours a strong bargaining position for both the entrees and the Mars local population. Ideally I'd like to see the return ticket + life support until the next return flight provided as part of the entrance fee to minimise risk, but there is still the problem of enforcing the contract.
[EDIT: I don't consider this a "fair" argument so I left it out, but as an aside, if minimising pain is your goal then mass sterilisation is the optimal strategy IMO -- there is no reason to continue the human race which will certainly produce millions of people in pain -- and if you have another goal which requires human existence to fulfil, then decreasing our extinction probability should be a huge priority]
> The scenario in which the bet does not pay off results in 1 million people and their descendants being stuck in a terrible situation, with distance making aid or relief impossible at scale.
We accept that in Syria already, and the potential upside's a lot bigger for Mars (survival of the species if Earth gets clobbered).
Which is a long way of saying that I may not be one of them, but I sure as hell will feel sorry for them.