People went into debt, and the prices of real estate and stocks skyrocketed. The policies pursued by Coolidge made the later stock market crash inevitable and depression inescapable. Credit expansion and inflation artificially reduced the interest rates, thus sending false signals to businessmen. Normally, declining rates would mean an increase in capital savings. Believing this to be the case, businesses increase production, leaving large inventories of unsold items.
More money leads to an economic boom, which causes prices to increase.
Each time prices increase for capital goods, used for business expansion, the costs of doing business increases. The prices continue to swell until businesses can't afford to remain in operation. In order to prolong the boom, more money may be injected into the system. This is exactly what occurred until 1929, when the Federal Reserve Board, scared silly of run-away inflation, scrapped its policy of easy money. All this after a failed attempt to do the same thing in 1928.