You have to deport at least some people.
If you allow everyone who wants to come here to come here, they would out number the native born.
It will be literally impossible to offer any services (let alone additional services like universal healthcare and free college) because there will be more free riders than tax payers.
You cannot just let everyone in.
At some point, you have to favor people who are already citizens.
I say we start doing it before the country is no longer economically viable, rather than after.
Jesus, undocumented immigrants are not "free riders". Do you think Juan from Mexico makes the enormous effort to get here and then sets up on a couch to eat Cheetos 24/7?