At least once a month, there is a big loss or gain to someone, based on a change in market valuation. That story though, is painted (if stippled) across *all* of the shareholders -- value gone from their net liq., because of a market turn. No one bought the other side of that -- there was *no*trade*! Just as big jumps make *all* shareholders "rich" and just as the '08-'09 financial crisis robbed a bunch of IRAs (and made a bunch of late-term investors into "poor" retirees.
The problem with investing in stocks is that at times, we survive based on hope. Whereas for trading, you don't bother about market crashing or not. Because every trading day is a good day. _____________
Sorry, but that's an entirely glib assumption that assumes $0 long/short in your portfolio, and constant liquidity. "Holding" is a fact of life. Back to the OP, "Holding long" means you're a'wishin' that the market recovers today, whereas "Holding short" means...... you're wishing the market continues down.