It depends what you call making money, I usually raise 3 pigs at a time from weaners, I look for them to be older , as in 12 weeks if possible, lots of smallholders have piglets that they cannot sell at 8 weeks, I raise them to about 60-80Kg a local butcher collects them has them slaughtered at our local abattoir £12 killing fee, our butcher prepares the meat £26.00 for pork or £46.00 for gammon and bacon and then I sell the meat in my village to locals, I usually make about £200.00 clear profit from 2.5 pigs and keep .5 of a pig to eat.
from my point of view this isn't making money because 4 months of trudging 3 times a day to feed and water them equates to about .20p per hour but I have a lot of fun doing it, it doesn't cost me anything and have made a whole new bunch of friends in the village and eat my own produce.
it would be very difficult to expand it out as well as outside my village the market is very limited
Personally I wouldn't have a sow or boar of my own, the cost of keeping them outweighs the cost of buying in weaners
Also the great thing about keeping pigs is to consider them pets you can eat!
Hope this helps