Explain why savings is important to capital formation?

In the classical model, saving is the only source of loanable fund. And the saving =investment becomes an equilibrium condition. But in the era of fiat money, the smart head is more important than the saving. Just go to the bank with your great plan,you get your investment done. And investment can manipulate the bubble which will get people rich for a while,until it bursts. But if you can jump on time, you will still be rich and be able to start the new bubble.