We always hear that the market is overvalued, that it's trading at 50x P/E or 30x P/E or whatever. This has been the case for as long as I remember (when it wasn't expensive, then the 'E' was too high and unsustainable etc.).
The market was expensive back in 1999/2000 for sure, but there were a lot of reasonably priced stocks. Ever since then, every time it seemed like the market got expensive, or when people point to the CAPE or some such thing pointing to astronomical P/Es, I made it a habit to step back from looking at the forest so as not to miss the trees.
A quick way to do that is to just look at the valuations of some of the large, well-known names to see if there is a bubble developing there. If not, like in 1999/2000, it may be just a small number of super-expensive large caps that are pushing up the P/E's of the whole market. If that is the case, who cares, right?