Unless you're extremely well capitalised, you'll be ruined by variance. If you can predict stock movements with 50.1% accuracy, you have a potentially profitabl

Unless you're extremely well capitalised, you'll be ruined by variance. If you can predict stock movements with 50.1% accuracy, you have a potentially profitable trading strategy. To make meaningful profits, you need a massive reserve of cash behind you. If you're right 50.1% of the time, you're still wrong 49.9% of the time. The wins and losses won't be evenly distributed. Poker is much the same, on a smaller scale. A professional player can turn consistent profits in the long run, but there's a huge amount of variance; they might have a mean hourly profit of $200, with a standard deviation of +/-$2000. You need a huge amount of capital to absorb that variance without going bust.