Rebbe Meir says, a man should ever teach his son a clean and easy trade, and pray to He to whom all wealth and property belong. Rebbe Nehorai says, I leave aside all of the trades in the world and I don’t teach my son anything but Torah.
(Kiddushin 4:14)
The Rema on Yoreh Deah 246:21 says one who is not independently wealthy should accept community support to learn Torah.
Rav Zalman Nechemia Goldberg (a prominent Yerusalayim Dayan, and son-in-law of Rav Shlomo Zalman Auerbach zt”l) was consulted by a yeshiva boy regarding his interest in studying medicine. The young man asked how the community to which he belonged could seemingly disregard our Sages’ admonition to take steps to remain self-supporting. Rav Goldberg responded with the following story:
A certain Jew once confronted Rav Elchanan Wasserman, asking how charedim could neglect the beraisa which says that a father is obligated to teach his son a trade. (Rav Wasserman, author of “Kovetz Shiurim,” was very adamant that Yeshiva students should strive to devote all their time to study). Rav Wasserman pointed out that this beraisa also compels the father to circumcise his son. As we know, if two sons die from this procedure, then the father should not circumcise his other sons (Shulchan Arukch Yoreh Deah 263:2). Likewise, Rav Wasserman saw that many young people died, that is defected from Torah observance, when they pursued trades.
In “Sippurei Chasidim” (Mishpatim number 198), Rav Zevin tells of one of the early Chasidic Rebbes, Rav Uri the “Seraph” of Sterlisk, who was asked how he could neglect his wife and children, insofar as his kesuba obligates him to work. Rav Uri pointed out that the kesuba obliges the husband to support his wife “bekushta” – in truth, implying that the search for truth (Torah study) has precedence.