Yes, there are lots of poor Mexicans. But Mexico also has an economy (GDP-PPP) of $1.073 trillion, which puts its economy at 13th in the world, ahead of Australia, South Korea, South Africa and the Netherlands, and just a small amount behind the economies of Canada and Spain.
...and if the relative GDP of countries established ANYthing, perhaps you'd have a point.
Yes, Mexico has a very significant business economy and middle class. The reason that is generally overlooked is because the only ties the horde of Mexicans invading this country have to that successful 1st world economy down there are geographic.
Successful, educated people don't pull up their roots.
The problem is the wealth is so highly concentrated with the racist light skinned spaniards. There is very little opportunity for anyone else.