Is the Syrian doctor's logic that sustenance is preordained and will reach him wherever and whenever (Syria or the Gulf) correct, and that there is no need to move for a better job?

It is authentically reported from the Prophet (peace be upon him) that sustenance is predetermined for a person, and they will not die until they have received it in full. Therefore, a Muslim should fear Allah and seek sustenance through lawful means, and not consider sustenance slow in coming, thereby seeking it through disobeying Allah. Sustenance seeks the servant just as their appointed time of death seeks them; even if they were to flee from it, it would overtake them. Nevertheless, this does not preclude diligence and exertion in earning and striving for what is beneficial. One should seek Allah's guidance (istikharah) and study their affairs to compare the benefits and risks of travel with staying in their homeland.