Why use credit?
Because liquid capital can be invested and earnt on. If you use low or zero interest credit to buy things, and invest your actual money, you actually end up with more money. I have had £30k on zero interest credit cards for about 10 years now, invested in accounts earning between 4 and 6%. I have to transfer the credit between cards every 2 to 3 years and that attracts a fee of 3%. So in effect I receive 3 to 5% a year on £30k I don't have.