I mean if you have a significant chunk of free cash sitting around there's almost no reason not to put a portion of it in 3-6 month Treasuries or something.
The return won't be much but it's better than letting the cash sit idle and evaporate due to inflation
Uh, that's not "better".
If you have a huge chunk of change sitting around, you've raised too much or too early, and you've successfully diluted yourself for zero reason.
If you actually had a reason to raise a lot of money, you'd do with the money what you promised the investors (who gave you the money) you would.
I've raised before. I raised what I needed. Not a penny more because I didn't need the money.