Why short the SPX?

I am a new tradingview user, and I see lots of post here telling people to short SPX.(Only based on their graphs...)
But the thing is, the FED plans to print money again. There will be more money in the market, then why will the SPX goes down?
The more money, the higher the SPX. (I believe...)

Please correct me if I am wrong. I am learning as well.