Subject: Re: The good old days ...
Now, since we all firmly believe in the value of a share, as opposed to its price, what to do when BRK is overvalued?

If you need the money for some purpose like kids' education or buying a home, go ahead and sell a portion of your holding. Otherwise sit tight and be prepared for lower future returns. I think this is especially a good option in taxable accounts where you benefit from deferred taxes if you are a long term stockholder.

In a retiremet account, taxes are not a consideration, so it is more an opportunity cost issue. What is your best alternative to Berkshire, all things considered? The answer is different for each person. For some it might be that Berkshire is their best option even at a slightly (hopefully temporarily) overvalued price.