It's not surprising -- it just isn't worth it for most people. To do it well, you variously need land; upkeep time; knowledge (pests you don't need, creatures you do, plant nutrition, how to harvest without doing damage, control of wastage, fertilizer issues, varietal information, home-cooking skills, canning skills); seed sources; patience; storage, fencing to control animal forage, sometimes a permit...
Yeah, not really. The knowledge is simple.
What you have to prepared for is losses. If you plant everything expecting perfect vegetables in a few months without doing anything else, you're bound to be disappointed. If you plant everything perfectly, and manicure them them perfectly, and expect perfect vegetables, you're also bound to be disappointed.
Home grown stuff has losses, always. Slugs are my nemesis with growing beans, but I grow enough of them (not much, only 10 plants or so) to make the losses less hard to bear.