I have successfully kept and bred bettas a few different times. The first time was back in the mid 80's, most recently about three years ago. I had a great time doing it. I never competed in IBC shows, but that would be fun to do.
If you want to do it for fun, by all means do it. If you are looking to make money, I suggest you pick a different fish.
Plakats will be easier to produce decent quality fish in numbers than half moons or double tails.
My suggestion if you want to raise a bunch of Bettas is to take them to a pet shop and trade them for store credit. Don't expect too much, as the stores can buy them in large numbers every week of the year from wholesalers that import so many fish at one time that the cost of importation is pennies per fish. Compare that to the $5 per fish you pay the Thai export, plus the U.S. Transhipper fee and domestic freight. The most males I ever raised jarred at one time was less than a hundred, so a far cry from being able to supply multiple pet shops on a regular basis. Yes, I have bought Thai fish, bred and raised some. There is a reason people still buy and pay all the fees to get Thai fish.
They are a very rewarding fish to breed and raise, and I am sure you would be able to sell a few to members here, or elsewhere, but unless you do a tub garden Summer extensive grow out, I would not count on breaking even.
So again, for the fun of it, 100% do it, for a money making endeavor, 99% don't try it.