The Fed creates (through digital ledger entries) bank reserves, which are NOT part of the money supply. The Fed has very few tools at its disposal, and money printing is not one of them. Also, the Fed looks at PCE to determine inflation, not CPI. CPI is more of interest to the government. Inflation and unemployment (Humphrey-Hawkins law in the 1970s) are secondary responsibilities of the Fed. The reason it was created was to prevent banks from succumbing to bank runs. It's there to protect the banking system.
Economies and markets move in cycles. We can't time those cycles precisely, but we can approximately. We can see when we are early or late in the cycle, and this one is clearly on its last legs. All the signs are there. I can't say for sure this year or next year, but no way will it go on for 20 years without a crash. One sign of a market top is when people throw in the towel and say, "This could go on forever" or some other long period of time. No, it can't.
Last leg? This isn't even parabolic yet. Can it last forever? Certainly not but it will last for as long as the fed has control and all indications are that they will throw a lot more money at this before it's all over. I wouldn't be surprised to see their balance sheet hit 20-30T over the next 10-15 years. Where do you think that money will end up? Yep - Stocks and RE. Valuations don't matter when the alternative is currency debasement. Yes, i know how that sounds but it is what it is. There will be a crash one day but it will be from levels quite a bit higher and the fed will not be able to stop it. Until then all selloffs will be quick and the recoveries to new highs even quicker. A lot of people's lives will be ruined when this is all over but owning assets will cushion the blow considerably, regardless of what the PE was when you bought.