I HATE the "CPM and a prayer" mindset that masquerades as a business model. I don't understand why anyone starting a business these days would rely exclusively

I HATE the "CPM and a prayer" mindset that masquerades as a business model. I don't understand why anyone starting a business these days would rely exclusively on ad monetization for their business. I personally would never invest time or money in any startup that had ad sales as the only source of revenue (and I've invested in magazines, fergoodnessakes!) I believe in MULTIPLE revenue streams. Most of my startups have charged directly for the product or service, but the most successful have all had multiple revenue streams. A startup I'm working on now, for example, has six distinct revenue streams...and there are probably others we haven't figured out yet. One of the revenue streams is advertising, but we deal directly with the advertisers (no ad network or agency taking a cut), there is a minimum $50K ad buy (reducing time/communications overhead), we have no dedicated ad sales staff (just 'order takers' and ad screeners) and it is our smallest source of revenue by a significant margin. There are too many opportunities out there to rely on the whims of the ad market.