You're still not guaranteed that by spending $400 per hour on one person with excellent credentials you will have a better outcome than with 4 x $100. There is also a balance of risk especially on longer term projects, with the 1 x $400 person there will probably be less technical oversight and also if they get ill or leave then the project is is serious trouble.
I'm not advocating employing talentless monkeys, they still need to be good at what they do but from a business perspective it's a more complex and wider ranging decision.
If you spend a lot of money you're not guaranteed to get the best. But if you go cheap you are nearly guaranteed to get a bad developer/product/whatever.
I'm not advocating employing talentless monkeys, they still need to be good at what they do but from a business perspective it's a more complex and wider ranging decision.