I had found some answers.
In the 15th and 16th century some germans are great merchants. With an excellent knowledge about sea routes and cartography. This knowledge is very appreciated, specially by portugeses who begun their expeditions. In 1538 a german named Johan Cromberger opened a printing shop in Mexico.
During the religious wars. Some flee the persecutions to the new world.
At the politic level. "Germany" of this time have many political systems, and many states. Some flee their country to find a country with more liberty. Free of the old europe.
Who leave germany ? a peasant ? nope, a dude who is able to work far away whit his own knowledge. Artisan, minor ect ...
Sorry for my level of language. I am not that good in english. But this is finally for the same reasons as many europeans.
My source, in french ofc.
http://www.persee.fr/doc/globe_0398-3412_1969_num_109_1_1030