I sat in on the venture class at UChicago last night (I'm auditing the MBA program).<p>They actually talked about this and the professor referenced some study out of UVA of successful entrepreneurs and one of the recurring traits was that their investments are guided not by the size of the opportunity but by their own conception of 'acceptable loss'.<p>It was emphasized multiple times that <i>you really should _not_ fund your venture on credit cards</i>, 2nd and 3rd mortgages on your homes, etc even if you think an opportunity promises to be the next google, twitter, whatever.