How can people justify studying Torah all the time?

 https://ohr.edu/ask/ask003.htm

"And not only the Tribe of Levi, but any person whose spirit moves him to separate himself and stand before Hashem, to serve Him in order to know Him...behold he has become sanctified as the Holy of Holies, and Hashem becomes his portion, his inheritance for ever. And He will provide his basic necessities for him in this world, as with the Kohanim and Levi'im..."

Rabbi Moshe Isserlis (Rama) quotes Maimonides' first statement, that encourages earning a livelihood. He notes, however, that there are dissenting views, and that their opinion is the one that "all places in Israel" have adopted.