The Rambam proves his point by the fact that our tenoim had an occupation.
But again, we don’t paskens like that.
What about, kol torah shein ima melocho sofoh betela, if no work is supplemented with Torah, that learning will not continue, Pirkei Avos (2,2)?
Do you think the gedolim such as R Aharon Kotler and R Moshe Feinstein, (let alone רבי נהוראי and many others onward until contemporary times) who advocated for people to learn full time, missed that?