All I hear from you are supposed government numbers indicating the positive or negative effects of illegals on the system. You come here illegally and you apply for or receive benefits, you are getting what you are not entitled to because you should not be in the system. Period.
There is a best meaning for the word immigration and that is select the best reject the rest.
Immigration is not a policy of, ok you made it here so now what do we do with you. It is a policy of you think you can hang with the best? We will decide if you pass the test.
Why do I say this? Because you are asking a country to take in an unknown if you accept no controls. Allow this policy to reject the unknown bad or good from other lands that we have no reason to incorporate, until we judiciously allow.
I think the judiciously allow part might be hard for you?