17th century American settlers were fleeing an environment where the child mortality rate was at least 1/3rd even for the upper classes, nearly all land and wealth was controlled by inbred gangsters, and the penalties for petty theft or incorrect religious worship included public hanging. From that perspective, the risks associated with colonization may have seemed much more attractive than the best-case scenario of spending several more decades of poverty in the same village. At least once you were in America, voting with your feet and moving west was always an option, something that was already recognized by 19th-century European socialists as a unique factor in the development of the US economy.

Of course I'm also assuming that the majority of the colonists were not only dirt poor, but also ignorant and uneducated and shamelessly lied to by the promoters of colonization.