That is the time to sell. Let the risk-takers get a possible last few percent profits, but I took my nice profits now and no longer have any risk. Every day that risk gets far greater. Ahhhhhhhhhhhh, peaceful slumber.
If you factor in inflation, I doubt the Dow is at an all time high. Not to mention that they replace members of the Dow often enough to make the number meaningless.
Stop thinking like a small-time dweeb, and START thinking like an investor.....if that's possible for you.