With all due respect, to give a sweeping generalization of 60 million people as all supposedly being felons, living on food stamps, and blowing leaves for a living is absurd. I also don't understand why you assume most first generation immigrants stay, when they are incentivized not to as they age due to rising healthcare costs in the US and declining purchasing power. This is completely anecdotal, but in my experience the vast majority of the first-generation (aside from Cubans, Puerto Ricans, and Salvadorians) end up going back home as they hit retirement age, either to live off their investments or/and their US pensions. It's their children, who are often completely Americanized, who end up staying within the US.
I can also concur with
@scary_robot_music, I've met many people who rotate between their home countries and the US or Spain. They usually work for a time to gain some-sort of capital, which is often sent back home as remittances to build a home, business, farm, etc. The reason for this is that gaining capital organically in Latin America is difficult without proper connections or being apart of the elite, therefore working overseas for a time is always seen as a quick and more attractive alternative.
The problem is now this is going to become less and less possible. More people = cheaper labor, and as inflation rises the benefits of doing rotations or even living long term in the US will become less attractive as the years go by. This is ultimately going to leave a population of disgruntled ignoramuses (in the US), which will sell themselves to the highest bidder (Democratic party/shadow elites) to survive.
Regardless, at the end of the day I understand your frustration, and agree that the US border should be controlled and immigration radically be curtailed (which has been discussed ad nasuem here and on RooshV), but I would caution making such sweeping condemnations of people, especially when many of them simply want to live better lives. Of course, it would be better for them to push for changes in their own countries in order to make this possible there, but hey, human beings will always take the path of least resistance, especially when it's made easy for them.