Even before liberal billionaire Tom Steyer was shut out of the next Democratic debate, there were tell-tale signs his rocket-fueled six-week presidential bid was failing to launch.At last weekend's Democratic National Committee summer confab in San Francisco, Steyer's home turf, his campaign had a fancy booth complete with a snazzy "Tom2020" photo backdrop, but only a handful of supporters were happily snapping pics and there were no sign-waving foot soldiers to compete with Kamala Harris' k-hive entourage.Still, just before his remarks to the gathering, there was a slight buzz in the...