I'm a big proponent of the bear case, but if you factor in dividends [0] pretty much any time in the last century has nominally been a good time to invest in the S&P 500 even if the first few years aren't optimal.

The bear case is generally "this will cause a crisis, then the government is going to print money, hand it out to asset owners & lump taxpayers and citizens with the real costs". There has been a reasonable expectation that shareholders will come through fine since the '08 crisis firmed up expectations about how the government will handle problems. I don't think there is an expectation any more that the S&P will go down in nominal terms. To argue that it will someone has to come up with a theory where the Fed doesn't get involved. There have been multiple major crisii and if anything US stock market performance is the inverse of how the economy is expected to perform. For example, COVID was a big winner for shareholders and asset owners despite obviously being an economic catastrophe.

[0] https://www.slickcharts.com/sp500/returns

Economists have predicted 9 out of the last 5 recessions, as the saying goes.

Usually even if this it the case you don't necessarily want to pull out of the market, but buy into the dip. Unless you seriously think the stock market is going to be wiped out for years, buying the dip means you have a large position when the market starts recovering.

Most non-institutional investors rarely just have cash lying around. My assets are tied up in the market. Same as it's dangerous to try to time the top of the market, it's dangerous to try to time the bottom. I tried in a modest way in 2008, and it took me a decade to recover on those stocks.

It's also dangerous because the dip is the average. Individual companies can and do fail.

Yeah when I say buy the dip ideally you would buy an index fund. Picking winners is a fool’s game anyways.