The investing statistic on winning investments and making money I find interesting has parallels to tennis vis-a-vis winning matches and winning points.
Rodger Federer over his career won almost 80% of his matches yet only won 54% of his points. In the S&P 500, 50% of the stocks decrease in value each year, yet the average year the market goes up. Since I don't have the ability to cut my loses and get out, nor the stomach to watch half my stocks go down, 80-90% of my investments are in broad based funds. The rest is used for entertainment by investing in individual stocks, where my deficiencies in investing won't make or break my portfolio.