For me the answer is "not a damn thing." D.C. has a ton of immigrants from all over the world. So do the other places where I spend a fair amount of time. I've not lost a job to an illegal immigrant. None of them have come traipsing through the neighborhood. No lost benefits, no longer lines anywhere, and I don't see that my taxes have gone up so as I'd notice because of them.
I could write a novel about how illegals have negatively affected me. Honestly, I find it very hard to believe you haven't been negatively affected; I'm pretty sure you're self-manipulating.
I'll give it to you in short without nitpicking the smaller stuff:
Higher taxes
Crowded emergency rooms
Extreme traffic on roadways
Slower response times from fire and police
Trash and Bud Light cans thrown out on roadways
Trash and dirty diapers left on our beaches
Old couches and mattresses thrown out in vacant lots
Graffiti all over the place
Degenerate filth loitering at every Home Depot and pissing in public
Abandoned stray pit bulls and chihuahua's run the streets of ghettos
I've had to send my three kids to private schools their whole lives to keep them from the filth at $2,000 per month
Uninsured and underinsured drivers on roadways. (Family has been hit three times by illegals without insurance)
Real American's who speak English in Southern California feel like foreigners on their own soil
My high school age kids can't get work experience or entry level high school age jobs because illegals have made burger flipping a career job
Again, I could go on and on...but hopefully you get the drift by now.