Yes indeed, an illegal immigrant typically works and pays taxes (strictly sales tax and the like, mind. Obviously they don't pay income tax). They tend to work unskilled jobs for greatly reduced pay, benefits and in substandard conditions. Jobs which would otherwise be worked by a legal worker for at least minimum wages, benefits and conditions, and who would be paying income tax on those higher wages. That is not, in fact, a good thing for society. For rich people, yes, obviously it's great for them, not so much for everyone else, especially the poor. Just look at unskilled farm work, for example. It's almost exclusively done for an absolute pittance by illegal immigrants, while the rural poor are all chronically unemployed. Good for the land owners, far less good for society overall. On a slightly related note, perhaps this, and not "being brown and speaking funny" is why poor rural Americans seem to hate illegal immigrants as much as they do. Just something to consider. But no, surely it's all about race, right?
Furthermore, all countries have limited infrastructure, employment opportunities, housing and the like, and therefore controlling their own immigrant intake is in their best interests. This is not "racist", it's simply good governance. As before, the US having little to no control over its own borders is not a good thing for society. For rich people, yes, they certainly benefit. Society, not so much.
As for the illegals themselves. Well, if you wish to move to a foreign country, go through the proper channels. If the country you wish to move to does not want you, move elsewhere. But don't cross the border illegally, build a new life for yourself, then act surprised when your past catches up with you and you end up deported. I mean really now, how the fuck else was that ever going to end?