What is the best thing to do with cash when the stock market is high?

1. Either hold cash- to buy the dip/correction/incoming recession

2. Contrarian rule- rebalance portfolio towards safer assets like bonds(if you anticipate stock market to come down ahead)

Value investors probably would sit back and not make buys during the boom, capitalizing on overvaluations perhaps to sell some of their stocks. Generally(including value investors) will practice 1 and 2.