I think this is more of a challenge of psychology. You need to mentally flip red numbers from “losses” to that asset class “being on sale”.

Let me explain:

• In the long run, all asset classes will see gains. We know this.
• The price of assets only matters when you buy or sell.
• We know that different asset classes are partially uncorrelated—in fact, the less correlated the better.

Take those three points together and you’ll realize that rebalancing a portfolio to sell off “winners” to buy “losers” is actually optimal. In the long run, the asset classes will see their average long-term returns, but when you rebalance, you’re always selling high and buying low. And those assets you pick up “on sale” will, on average, outperform.

The less popular view I have is to keep 0% cash and 0% bonds on long investment horizons, which means all retirement funds. Even when you retire, you still will be drawing down for a long time. Long enough for stocks to outperform.