It can be done. But it requires a lot of work. When you aren’t in the fields planting/fertilizing/harvesting (which takes up a lot of time on its own), you’re gonna be slaughtering animals, preserving foods (through canning, salting, etc), doing repairs to the farmstead. You’ll be up frequently from before sunrise to after sunset. You’ll have some leisure time, but not a lot. You probably won’t be traveling as much (a trip to your state’s capital or largest city will be a big deal). Modern gear like tractors definitely helps, but it introduces its own complications (namely fuel and maintenance, how will you be paying for that?). Pesticides can cut down on crop losses, but they can also literally kill you (seriously, pesticide poisoning is one of the most common forms of suicide, and some insecticides are basically nerve agents). And all this effort can be for naught if there’s a late freeze (you did can your extra food, right?).

That’s not to say there isn’t value in a lifestyle like this. But it requires a lot of effort that many people either don’t want to or cannot put in.

Do a bit of earnest gardening and evaluate your yields. Consider these in proportion to what you buy at the grocery store each week, and the land/resources required. Math it out. Probably not impossible, but certainly not trivial.