I don't need yachts or private jets to be extremely happy. In my country, 1 million would be enough to change anyone's life (liquidate mortgage, invest a part to get passive income, and keep working in something you really like, even if it is poorly paid, and you have guaranteed a fulfilling life). I will even say more: above that prize, I don't think the level of happiness will increase.

Maybe 2 millions, so I can also free the next generation? I'm not sure about it: chances are that my children would grow up spoiled. I might keep the second million to counteract the effects of inflation, and that would be all. About the remaining, I would have to see myself in such situation, but I think that the best decision would be to donate it to relatives, close friends, a good cause... so even if I won 65M instead of 100M, better: it would mean less worries