I am not a smith, so some of what I say is speculation, some is observation, and some is based on experience.
Blacksmithing requires bigger, heavier, and more expensive equipment than stock removing. A forklift may be required to move the equipment. Generally, the successful blacksmiths use power hammers and hydraulic presses. Smithing also requires an outbuilding, whereas a stock-removal maker can comfortably fit in the basement of a house.
My point is that smithing has a higher start-up cost, and also a higher monthly overhead cost (the workshop etc) than stock removal.
I think most self-employment endeavours that involve crafting a physical good will take several years to break even. So you'll either need to start with a big chunk of cash, or you'll need to work a day job and feed money into the business. I did the latter for two years before I broke even - it would have taken me much longer if I had to pay rent on workshop space.
For the same money and time, you could buy a Tormach CNC milling machine for $20K and bid on general small machine. Your niche would be runs of smaller parts in quantities less than 20. Whatever you do, my advice is to be ambitious, but bite off what you can chew. Businesses, just like people, must live within their means.