I'd even push it a little bit and say not even groupthink necessarily, but really the major issue here was a fundamental lack of diversification. Groupthink may be a lack of diversification in terms of opinions/ideas, which certainly is dangerous, but in the SVB example, there was also quite a clear and real lack of diversification of depositors.

If you go back in US banking regulation history, there used to be very strict rules around branching (which is one of the reasons why there is such a large number of regional banks in the US). This had the side-effect of preventing banks from having a diversified set of depositors, so local shocks (crop issues, weather, etc.) were much more likely to decimate small, local banks, which is one of the reasons why bank failures used to be MUCH more common.