Would illegal immigrants stay a “cheaper, faster, and stronger work force…” if given amnesty?

Someone said they were ‘pro-illegals’ because they are a “cheaper, faster, and stronger work force”. But if you check back in history when slaves were not considered citizens they worked their butts off because it was survival(you don’t work, they kill you). They were given freedom and citizenship and now you can’t get half of them to keep a job.

History repeats itself… Wouldn’t the same thing happen to the illegal immigrants?