So humans have historically eaten a lot of plants. No doubt ground nuts, cattails, etc were eaten by someone. Starvation is bad time.
As we've moved forward into modernity, the "most suitable" options were selected out of the others as farming is quite a lot of work. Most productive/easiest to grow win out in the end.
The issue with many of options we don't traditionally eat comes down to life cycles of the plants, effort to prepare for consumption, or unreliable quality.
As an example in North America, acorns are edible. The native people here before European colonization very much ate them. But: Oaks take years to mature, maybe 1 in 10 actually taste ok (the rest being bitter), are a bastard to harvest from the tree, and don't typically bare all at once (Just generally throughout a season) What this boils down to is, a nice addition to a harvest if you know what trees yield good acorns, and happen to be nearby to catch them when they start dropping before wildlife eats them all. By the time North America sees large static human populations requiring a large, stable supply of food, humans had found other options (Squash, Beans, Maize; things that became mainstream domesticated crops due to their being easier to farm) Ultimately, all crops started as wild strains, and human selection began bending them towards being more useful. Wild Almonds have about the same chance to not be toxic (even domesticated ones have some cyanide) but because they were selected for early (thought to be done accidentally as early agriculture develops), by the time humans need larger scale agriculture, they're "conveniently" ready to go.
Capitalism has little to do with it early on, but later efforts around improvement (hybridization and later genetics work) are certainly driven by profit motives just as much as a desire to produce more food.
Tldr: they're definitely edible. But since we didn't really attempt to domesticate them (because of timing or general human nature to make our lives less difficult), they kinda suck compared to more mainstream crops. Capitalism increases this divide as we apply modern understandings of selective breeding and genetics to the naturally occuring modifications humans were already driving.