Last time I looked, there seems to be a couple of gemoros who deal with this…Have you ever learned the mishna in Kiddushin ? “Chayiv lelamdo umnus” …Maybe you only learned berochos..oh, do you remember the gemoro about “harbeh osu velo olso bejodom”?
The fact is that it is not a mitzvah for EVERYONE to learn all day. It is not something that ever happened in Klal Yisroel and for a very simple reason….it is not practicable or feasible!