Investing in your own education is one of the most important things you can invest in, with the greatest returns.
However its often hard to pick the next trend, who would have known that COBOL programing will become popular again as the world was amassed with hysteria over the y2k bug. That might be a distant memory, and COBOL programmers really aren't that plentiful anymore, but just goes to show the future is so unpredictable, so hard to see what will be the next winner.