I do not understand the mathematics behind the dilemma. I'm assuming only the firts chicks cost money, because down the line they will breed.
But feeding them, housing them - vitamins and doctoring costs a lot of money.
So anyone with couple or more chickens - how much does it cost to have them on the table? And realistically how many eggs do you get?
Those chicks at the supply store are for small hobby farms. The rotisserie chicken comes from a big factory farm. That factory farm either doesn't have to pay for chicks at all (they just breed their own), or they buy them for a fraction of the retail cost by buying them in bulk directly from suppliers.