Ben's emphasis was on protecting his expectation of profit with minimum risk.
We get a feeling, if we can, about what we think the company is worth.
Making a decision to sell is the most difficult thing we do.
One has to know more about a company if one buys earnings.
I agree with Warren to keep it simple and not use higher mathematics in your analysis.
If the market is so cheap, you want to get something with a little more zip in it, or potential.