If anyone in this life is totally self sufficient, I haven't met them yet.
For my partner and I, we started the journey about three years ago. We live off grid in a 700 sq ft cabin. We have well water, power everything with solar power, and heat our home with wood.
Our goal is not total self sufficiency, but rather to slowly but perpetually gain skills that allow us to check things off that we now do not have to buy at the store/from major corporations. And to withdraw from systems we disagree with. Real life example. I learned to use a chainsaw and fell trees. Now I don't have to pay the gas company for heat. Or raising chickens for meat. I have not bought chicken at the store for a little over a year. I no longer participate in the factory raising of chickens. But I had to learn how to process and preserve them first.
In less than 3 years we have built 2 gardens, 3 animal houses, propagated shittake mushrooms, installed a solar system, cleared a pasture, raised about 200lbs of meat, hand split four cords of wood with a maul, etc. We currently keep quail, laying chickens, seasonal meat chickens and rabbits for meat/pets and guineas for tick control. Also a couple dogs. We are more self sufficient than ever, but NOWHERE NEAR total self sufficiency.
The challenges are well, EVERYTHING!! I grew up in Brooklyn, NY and didn't get my hand on a power tool or a fresh egg until I was well into my 20s. The challenge, for me, is a large part of the draw. This lifestyle offers a beautiful equation where ones problem solving skills and work ethic will directly corrolate with their quality of life. Try finding that at a conventional job...
As far as making a living. I think it will take a while, and I will never get rich. My current goal is to make my animals financially self sufficient. So if I din't go to work, they could still eat and feed me. It takes creativity. I partnered up with a CSA and they are a regular customer of my eating eggs. They sell for 3 dollars a dozen, about 7 dozen a week. Ok, that pays for layer feed and bedding. I sell pickled quail eggs (just started) for 10 dollars a jar. People who like these seem to LOVE them and I am getting almost a dollar an egg this way. My CSA connection may be interested in them by the case. If so, the picked quail egg endeavor would tip my animal financials into the green. I am also breeding rabbits mainly for meat, but I sell a few to pay for feed. If I am getting food for myself, and the animals are eating free, I consider that making money. For now, I also work 2 days a week.
I guess for me, ultimately, every endeavor I have taken on in my life has been challenging. What they always lacked was fulfillment. I find it much more challenging to work a 9-5 and spin the hamster wheel of rent and bills and not utilize my mind and body to the fullest. That is a pill, I learned at huge detriment to my mind and body, I just couldn't swallow. I find it much easier to live with myself and sleep at night embracing the challenges and rewards of the homestead. Even though it is REALLY F-ING HARD! I am grateful everyday to be the steward of this land.