i really really really don't understand this stuff, it makes no sense

simples - money in their account earning interest is better (for them) than sitting in your account also they deem it that if you can afford to have money sat in the account with them, you clearly don't need it yourselfsimples - money in their account earning interest is better (for them) than sitting in your account also they deem it that if you can afford to have money sat in the account with them, you clearly don't need it yourself