Because the Internet is still uncharted territory, no one can predict how long it might take for the large sites to become profitable. Although stock prices are high, profits are often non-existent. Many have realized a profit, and others are have found their sites useful for reasons other than generating income. But lots of online businesses, just like those that function off line, don't make it. Poor planning, inadequate research, and under-capitalization are often the cause for failure.
Business is about making money.
No matter what other ideals you bring to the venture, if it doesn't make a profit, you don't pay the rent and your business will fold. If you are a micro business owner, you are going to experience a lot of financial discomfort along the way. Figuring out where that profit is going to come from is essential. And that profit won't come without investing lots of time and effort into marketing your business. Enthusiasm and a burning desire to make your business work will go just so far.