One thing I've definitely learned is it's easier than you imagine to scale a good business into a bad business. To over-invest in something that can't or shouldn't scale as quickly as the new investment pressures now dictate.
In business there's the subtle art of keeping expectations and results in healthy alignment. I think there's more pressure to avoid having too little investment than too much, but both can kill you. And it's SO brutal on morale when doubling revenue feels like a failure because 5x was the wildly-unrealistic demand of your pretend valuation.