If it is irrationality, it seems like a huge case of mass-hysteria is happening!
When would it be time for you to consider adjusting your framework here? Is there really enough variation in the obervables here to justify seeing each company as its own fully-personed snowflake?
It does seem like a case of manic activity not unlike the overhiring that brought us to this point in the first place. As far as the economic validity of anything happening, who knows. I know better than to bet against the irrationality of the market.
Behavioral economists have ascribed economic bubbles to the same root causes as mass hysteria. Humans may become more sophisticated, but the tendency to believe in collective delusions are rooted deep in our psychology.
When would it be time for you to consider adjusting your framework here? Is there really enough variation in the obervables here to justify seeing each company as its own fully-personed snowflake?