A lot of people would pay a lot of money for a reputation for being more fearsome than fear itself. Speaking entirely in terms of money, I think that this was probably a clear cut good idea, because in the long run, for Harry, money is likely not to be a limited resource in practical terms. Sure, millions of dollars worth of gold could theoretically be used to save a lot more people, but Harry doesn't have management of his account for the time being. By the time he's old enough to actually access his account at will, his debt to Lucius is likely to be a triviality, or already dispensed with.