In other words, SVB was willing to shoulder a greater amount of risk than the more staid banks. There's nothing wrong with that at all -- but taking on more risk is taking on more risk, and sometimes you end up getting burned by it.
So the argument that by the mere fact SVB banked startups as customers was more risky than big banks is not quite precisely right, as big banks have business accounts and plenty of startup customers too. But as other comments have mentioned things were often made quite hard for them there, and SVB was the better product to startups...as just a literal checking account for day to day operations.
The giant risk management failure was in how SVB managed the deposits and indeed the mismatch of the assets it held against them. We all know the long dated UST issue now. Their deposits ballooned so quickly over the last 18mo, the mistake was to put them into such long locked up bonds immediately. A better approach could have been to assume that money could "come out as fast as it came in", and to have held shorter duration securities, shorter maturity bonds, money market funds, repo market commercial paper etc. Then as the steady state pattern emerges post this influx of deposits, then make a better risk management based decision of what proportion to now put in longer dated assets, medium dated assets and shorter dated ones.
And above this specific risk, clearly in hindsight, there was an overall systematic risk in having a non-diversified customer base who all consume the same information sources, highly networked and correlated with each other in their behaviour.
I think from their perspective, they thought they understood tech better than other banks, so thought that they could better analyze the risk (thereby not misclassifying many companies as risky) and use that as a competitive advantage. Right now, it does not look like that part of their business model failed at all.
Just because one is conservative, does not automatically mean one is not taking on risk.
In banking, interest rate risk is the exposure of a bank’s current or future earnings and capital to adverse changes in market rates. If they put all their money into govt backed securities, they also took on portfolio risk.
Cash on hand would clearly help with a bank run and could be slowly invested in treasuries over a longer duration.