A similar thing is said here in europe but an important caveat is that they typically had no way of drawing most support. No commonly accepted way of regularisation. Buying property. Etc.

One can easily go back but will more easily go back if there's no point in staying beyond the momentary moneymaking and essentially just no future.

It's imo how china manages to have roughly as much migration as Berlin despite sharing a border with pakistan, afghanistan, etc and without large militarised force to kick people out. Simply don't give to incentive.