Looking to put your life savings into an unproven start-up, and hopefully cash out when it hits big?Rules under consideration by the Securities and Exchange Commission would allow start-ups to "crowdfund" their businesses, raising capital from people who have traditionally been barred from making such risky investments.But while the crowdfunding phenomenon (essentially raising small amounts of money from a large pool of investors) has worked for companies like Kickstarter and Indiegogo—which fund specific projects like films and music, trying to fund start-ups this way could prove disastrous for many people, experts say.