If you want a tidy snapshot of what it’s like investing in the stock market, check out how things have progressed so far in 2025. The S&P 500 is up almost 13% for the year and recently hit an all-time high — just a few months after a steep sell-off had many experts warning of a coming bear market. The lesson is that you can never tell how the stock market will react in the short term, but you can usually depend on it to keep moving higher over the long term. So why do so many investors still end up losing ...