"Geez, these humans (immigrants) are going to cost us 18 dollars a year to invest in their future like at one time Americans took a chance and invested in ours - the bloody cheek of them!"
You have on your borders the greatest resource you could get - humans.
I could find you a field 5 miles square. Return in 5 years and not a lot will have happened. Fill it with 10 million humans however and give them all the resources they need and there they will build a shining wealth-creating city full of industries people on their way up.
Once you have humans, give them the resources and they will do the rest, cos that's what humans have always done - create!.