Studies show otherwise. For example buying a new 52-week high on the S&P 500 futures is a losing proposition. In fact you wouldn't believe all the nonsense most traders take for granted.
I'd love to see the studies that prove buying new highs is a losing proposition. Buying a new 52-week high on the S&P has been a winning proposition for just about everyone so far. Three of the most profitable swing trades I ever had were buying right after new highs were printed. What's funny is that one of those trades was a thinly traded stock and I accidentally placed a market order instead of a limit order, and immediately caused price to run more than 3% into new 52-week high territory. It continued to make new highs for a few days before a shallow pullback.
Buying highs is part of the game, what the higher TF's context is and what price does above that high should be your concern.
There is an old saying in Wall Street : "Amateurs buy 52-week high breakouts - and breakouts in general - , the pros fade them". Enough said for the time being ...
Read "How a Second Grader Beats Wall Street: Golden Rules Any Investor Can Learn" for example, it will show you numerous studies that show exactly that, among other things. Sure, any idiot can make money during an uptrend. But backtest that theory with 30 years of S&P 500 data and see for yourself...
They weren't paying attention so they did not hear the big bell the exchange rings to announce that the market has topped.