Just a simple What If question: a highly advanced alien species makes contact and offers humanity the technology and know-how for space travel (Star Trek-Mass Effect level) but the cost is that they want one million civilians for experimentation in their science division. It's a one-off amount, and a one-off opportunity for trade. Reject the deal, they leave and that's that. Accept the deal and start colonizing space within ten years.
Would it be worth the cost?