You could do a pretty long thread on "signs of the times" suggesting we are seeing end of cycle.
* Meme stocks are back.
* US average tariff rate just popped up above the rate right after the 1930 Smoot-Hawley Tariff went into effect. The 1930s were so great.
* The regulatory gloves are off in crypto. ("Everything you don't understand about money, combined with everything you don't understand about computers"--John Oliver in 2018)

Even on a short term basis, omens are not great. Breadth appears to be rolling over even as the markets hit fresh highs. It doesn't mean a market top, but most market tops do include that.

Personally I would not say we're at the stage of recommending heading immediately for the hills, simply because insanity can really go on for a while sometimes. As a gut feel, to me the mood seems more like early 1999 than early 2000, more like mid 2007 than mid 2008. Crypto developments seem more reminiscent of the introduction of CDO-squared, not the start of the defaults.

Another interesting effect is the "K shaped" economy. There are arguably two entirely separate US markets, divided by politics. One set is very bullish and optimistic, the other is battening the hatches. The companies and securities that cater to the two groups are seeing diverging business conditions. Pickup truck sales are booming, battery EV sales are flattish. If you consider the US as having split into two markets, it's conceivable we might observe a recession and bear market in one but not the other : )

Jim