One million will not cut it. Greenland has free healthcare, free education, and a whole host of other social benefits that, over a lifetime, give a lot more value than a million in hand, and the US social system does. In addition their current (danish) passport ranks higher (4) than the US passport (9) in the The Henley Passport Index [1].

[1] https://www.henleyglobal.com/passport-index/ranking