how else can you have capitalism?

if you labor for fair and livable wages it will be hard to save up capital to compete in the free market.

you will have expenditures such as food, shelter, and entertainment to pay for.

usury or loans with interest give you leverage to take manageable risks for rewards with capital.

if your business fails you pay off your loan with interest and then try again with a new loan.

a loan with interest allows you to still have the safety net of your savings, instead of putting it at risk to compete in the market.