This gets you into the investment habit. You build your investment steadily, without putting too much or too little at the wrong time. The needs and demands on your income differ depending on whether you're just starting out, raising a growing family, putting children through college, in your prime earning years or getting ready for retirement. People with lots of discretionary income can afford to take greater risks with their money than people who are just getting by or who depend on their investments for their income. The more assets you currently have, the more risk you can probably afford to take.
Some people are comfortable with high levels of risk.
Don't do anything you're not comfortable with. Home Page Buy Low. But it's impossible to determine exactly the right time to buy or sell. The best way to gauge a stock or mutual fund's performance is to compare it to a benchmark. The various industries and market segments also have their own indexes.