Is zakat obligatory on money saved for living expenses and studies, given that there is currently no employment and no knowledge of when sustenance will come?

Zakat becomes obligatory upon a Muslim if they own wealth that reaches the nisab (minimum threshold) and a hawl (one lunar year) has passed on it. This is based on the Almighty's saying: "Take, [O Muhammad], from their wealth a charity by which you purify them and cause them increase" (Quran 9:103), and the Prophet's (peace be upon him) saying to Mu'adh: "If they do that, then inform them that Allah has made obligatory upon them a charity from their wealth, to be taken from their rich and given to their poor." Paying Zakat is an act of piety towards Allah, and Allah makes a way out and provides relief for the pious. Spending wealth increases it and blesses it, as the Almighty says: "But whatever thing you spend [in His cause] – He will compensate it; and He is the best of providers" (Quran 34:39), and the Prophet (peace be upon him) said: "Charity does not decrease wealth." It is not permissible to reside in non-Muslim lands except out of necessity, as the Prophet (peace be upon him) said: "I am free of any Muslim who resides among the polytheists," due to the harm this entails for one's religion and morals.