fed back stop has a huge downside

if we have massive PE expansion and market rips higher then FED may have bigger problems at hand..since FED has been worried about the downside, if the market burst from higher levels it would be even more catastrophic...if indeed the least path of resistance is up, what would prevent traders to ram it up? Last wk action has firmed up bullish conviction so unless we see significant sell off, dip buying is all that will make money...