(Context: Price spirals only go upward in all industries. Someone said it reminds him of stock market roundtables in 2001)
It probably referred to the bursting of the tech bubble around 2001. Before that, the mood was also very much "it can only go up!!!". It probably meant that one should be a bit careful with such statements, as that’s roughly what is said in every bubble (see also the real estate bubble in Japan in the 90s, or the precursors to most stock market crashes).
On the other hand... often there is a spark of truth for a longer time. People have been telling you for 10 years now that real estate prices "have to" fall. That interest rates have now finally reached a minimum and really can’t fall any further, by the way, has also been said (I remember a discussion around ~2011 as an intern with an older colleague who had just finished building his house... he also opted for long-term fixed interest for that reason, because he was told this). That is also the main reason why I roll my eyes when someone says today "it was clear that interest rates had to rise!!!!!"
Hindsight is always 20/20 ;)
On this topic, I would like to recommend the book "Irrational Exuberance" by Robert Shiller (German title "Irrationaler Überschwang"). Even though every bubble is preceded by a whole bunch of good reasons and helpful factors (e.g., low interest rates), bubbles are always also a herd problem. At some point, the favorable factors disappear, but the trend still continues a little further. After all, many only entered shortly before the peak, and there are still some who want to get into the market. And only when these can no longer get in (e.g., because the bank at 3% simply no longer sees the creditworthiness that existed at 1%) does it start to collapse. First in the completely overheated markets. Now, Germany is of course not the USA and real estate is something different from stocks. If a real estate sale would realize a loss, often it is not sold but simply waited out. In the USA, on the other hand, one can hand the bank the keys and be debt-free. The downward trends are correspondingly more extreme there.