Why did european countries send colonists to the americas?

They were looking for sources of trade and new tools.  Most colonists and explorers were single men who were seeking their fortunes.  

"In general, however, most historians attribute colonization to mixed causes.  The thirst for land.  The need for resources to support growing populations in Europe.  The desire for new trade routes and luxury goods.  The ideology of existing slavery and indentured servitude.  The religious backing of a Church whose ideology seems to have changed to fit the circumstances and expand its pockets."

Reference:  Isselhardt, Tiffany R. “Why Did Europeans Want to Explore and Colonize America?” Owlcation, Owlcation, 10 June 2016

social contract theory, nearly as old as philosophy itself, is the view that persons' moral and/or political obligations are dependent upon a contract or agreement among them to form the society in which they liv