Imagine someone created a government agency with no other function but to hand out (for example) free AR-15s to anyone, just for the asking. I would really love to have an AR-15, but I can't afford one.
So, would I support the existence of this "wonderful" government agency?
Nope. I couldn't support a government agency; even one formed specifically to give me exactly what I want. Even if there were no strings attached, and no hidden agenda or unintended consequences to the recipients.
How can anyone? It's something I just can't wrap my head around.
Even if I believed a "border patrol" or "ICE" were necessary, I would oppose them because they are a government agency. They operate with stolen money-- money taken, at least in part, from people who don't want their "service" and don't want to fund them. That makes their existence unethical regardless of any other consideration. (And there are a lot of other considerations making them bad guys.)