The Fed is understandably worried that these bubbles will burst leading to another market meltdown. However, the boom-and-bust cycle will not end because regulators stop investors from taking "excessive" risks. Almost every bubble and economic downturn America has experienced over the past 107 years was caused by the Federal Reserve's manipulation of the money supply.
The Federal Reserve's actions artificially lower interest rates, thus distorting the signals sent by the rates, which are the price of money. Artificially low interest rates cause investments to be made in projects that are not supported by the real underlying market conditions. This results in a boom, inevitably followed by a crash, then by a new round of money creation and government bailouts restarting the cycle.