Why do investors suggest in purchasing select stocks after they have reached an all-time high as a criterium?

I agree with you 100%. When it comes to products and services we are the world's greatest shoppers. Waiting until they go on sale. Trying to buy at the cheapest price possible. But when it comes to stocks, everybody wants to know what the "hot" stock is. They want to buy Google or Apple or gold AFTER they've had a great run. AFTER their price is high. Just the opposite of what they should be doing. The best time to buy a stock is when it's out of favor, when everybody else is selling. I bought Boeing years ago when the airlins were in terrible shape when the plane manufacturers were in the dump. When Boeing was $26 a share. It went up to over $100 when I should have sold it, when everybody was buying. But I'm a long term investor and wasn't interested in paying the tax on it. But I'm still way ahead.