The concept of altruism does not factor into the equations illustrating the flow of capital between markets in capitalism. All the theories attempting to explain an individual's motivation to give money to one of these sights are only that- theories, all based in psychological speculation. Economic models rely on certain accepted realities to operate. One of these is that all consumers in the given market are reasonable, rational people, who allocate their disposable income for the sole purpose of maximizing their marginal utility. And in this case, people are not doing that. It's similar to when consumers make impulse purchases, compulsive purchases (like drugs or alcohol), hell, even drunken purchases on ebay, which I'm guilty of several times over. These result from hiccups in the human condition economic models cannot quantify, and therefore, cannot account for.
This is one of the reasons why the government is quick to jump in. Besides the fact this online crowdfunding forum presents problems for tax assessment and collection, investment regulation, and ponzi schemes or loan sharks, it's simply difficult to understand. The establishment is never quick to accept novel or game-changing ideas. The bottom line is, with the current administration striving to improve conditions for entrepreneurs and small businesses, they will more than likely look for ways to accommodate these forums rather than supress them, provided they can find an unobtrusive way to regulate them. While it may not coincide with my personal ideal of capitalism, it does help people out who need it, which is pretty cool.