It's not that they hate Mexico, it's just they love the free programs the U.S. has created, like free welfare, free medical care, free education, free housing, etc. And judging by the amount of Mexican flag waving recently at all the protests, I'd hardly say they hate Mexico, they just love free stuff more.
Most of the Mexicans don't even like America at all, they just like getting all the benefits. Given all the chants of "gringos go back to Europe" and "You stole this land", etc., most of them probably hate Americans. Although they say they love America and want to become Americans, what they're really saying is they love all the things that Americans have built and want stay here AS Mexicans but be entitled to all the things we have sacrificed for just by showing up and taking it.
And now that so many of them have been here for so long and gotten used to all the free stuff, they feel threatened when people say they should not be allowed to get all the free benefits or that the laws should be enforced and they should be sent home.
Surveys show that 25% of all illegal alien Mexicans are on some major welfare program, mostly due their prolific U.S. born litters, and they don't want that free gravy train to end, they've gotten too used to it. And among legal Mexicans the figures are even higher, like 1 in 3 legal Mexicans are part of some major welfare program. So when you see illegals waving Mexican flags and screaming in Spanish that it is their right to stay here, remember that 1 in 3 are on welfare, and what they are really saying is, don't take away all my free goodies, it is too good here, getting free stuff just for cranking out as many anchor babies as is humanly possible.
Center for Immigration Studies Report:
"Whereas 14.8 percent of native households use at least one of the five major welfare programs,
among households headed by an illegal alien from Mexico the figure is 24.9 percent. Illegal immigrants from Mexico primarily receive welfare benefits on behalf of their American-born children."
Report on Mexicans and Welfare Use (Means tested programs)
http://www.cis.org/articles/2001/mexico/means.5.gif
SSI - Legal Mexicans - 5.6% / Illegal Mexicans - 0.7%
Housing/Rent Subsidies - Legal Mexicans - 6.3% / Illegal Mexicans - 1.7%
Gen. Assistance - Legal Mexicans - 7.3% / Illegal Mexicans - 1.2%
Food Stamps - Legal Mexicans - 11.1% / Illegal Mexicans - 8.0%
Medicaid - Legal Mexicans - 29.3% / Illegal Mexicans - 22.4%
Any Welfare Program - Legal Mexicans - 33.9% / Illegal Mexicans - 24.9%
Unemployment - Legal Mexicans - 8.5% / Illegal Mexicans - 7.2%
School Lunches - Legal Mexicans - 31.8% / Illegal Mexicans - 37.4%
Earned Inc. TaxCredit - Legal Mexicans - 55.8% / Illegal Mexicans - 39.4%