I'm equally perplexed as to why people always seem to think a big downturn is right around the corner. Maybe there are always enough warning signs that someone with a sufficient penchant for confirmation bias will latch on to.

Regardless, nobody can tell the future - there are simply too many unknowns to consider. We will certainly have more good times and bad times. As to when they come, predict all you want, but historically analyst predictions have an awful track record (historically, expert predictions are wrong most of the time https://www.cxoadvisory.com/gurus/ ). The occasional person who guessed right previously (there will always be some) are then raised up as oracles.