I agree that the profit does not depend on the size of the business. However, it is only the ratio that does not matter but not the actual profit. Take for example a small business of baking at home and selling to the neighbors. The capital is $100 and the starting profit is $5 that later on the profit rose to $50. That means a 50% profit that can even reach 100% if there are more sales. Now, the capital of $100 earned a profit of $100 which may be the maximum. In a big business with a capital of $100 million that earns 50% profit would have $50 million. There's the difference compared to a small business.