Investing just means trying to turn your money into more money. When I say "poor" investment I don't mean that it's a bad idea but just that you can't reliably produce returns from that activity. If you could reliably produce returns from, say, playing slot machines, then investment funds would hire people to go out and generate those returns. Purchasing equity in a company is obviously very different legally but in the most basic sense you're making a bet that the company's shares are going to be worth more in the future.