This sounds like the proverbial crabs dragging the other crabs above them trying to get out of the pot back down with them.
Irrespective of were one falls on the illegal/undocumented immigration debate, and what the possible solutions could be, what does your post have to do with immigrants who spend considerable time, money and energy navigating the US immigration system that may feel it a tiny bit unfair when others don't have to abide by the same set of immigration rules?
I would add that for many immigrants to the US, especially those who are on the lower rungs of the economic ladder, the US immigration system isn't just a minor bureaucratic announce, it can be a significant source of financial and familial stress.
The cook doesn't even need to put a lid on the pot to keep the crabs from escaping, since as soon as any crab tries to escape, the crabs below it will drag it down with them.
Similarly, in the immigration debate (and in many other situations in life) those who are worse off often resent others who are doing better, and instead of helping to improve everyone's life, or at least focus on improving their own, will try to worsen the lot of those who are doing better.
I saw both the financial and personal toll that navigating the immigration system took on my parents, it was a constant source of stress in the family. I'm sympathetic to all immigrants, legal or otherwise, and believe that immigration reform should include amnesty for those in the US illegally, along with a path to citizenship.
With that being said, I would find it problematic to apply a different set of rules and expectations for different kinds of immigrants. As I said, I do support a path to full legalization and citizenship, even though I would personally still find it somewhat unfair. I don't think that this feeling of unfairness is resentment though, and I certainly wouldn't wish for any immigrant's life to be made harder or worse off than my own.