Exclusive Torah Study is not for everyone - Mishna Berurah

 Biur Halacha (156:1): Torah study without work becomes lost & causes sin -  The seforim write that this rule is addressed to the masses since not everyone is able to have the merit to exist on the high level to be involved exclusively with Torah study. However, there are always individuals who are in fact able to devote themselves totally to Torah study. [This is what is mentioned in Berachos 35b, “Many did like R’ Shimon Bar Yochai and they were not successful in Torah. That means that the masses were not successful in exclusive Torah study – but there were individuals who were]. And G d will surely provide them with a livelihood as the Rambam (Hilchos Shemitta chapter 13) wrote, “And not just the tribe of Levi alone…”  And it is obvious that if there already exist men who wish to support them in order that they devote themselves to Torah study that this directive to combine work and Torah study is not relevant. The proof for this is provided by the Yissachor-Zevulun relationship.