[mongol]

You can be a net positive one day, next day you lose your job and are not. On the other hand, permanent is supposed to be without end. An unemployed worker with no language skills in the local language quickly becomes a burden

Residency while employed is rational. If you want to stay longer, learn the language

[zerr]

One would say, unemployed with a good local language skills will be able to easier navigate bureaucracy and claim more benefits - more loss for the state :)