I think the difference for me here was that they took money to create a known solution to a known problem. Theranos, on the other hand, seemed to have claimed to have already had a solution, when in reality they were pursuing an unknown solution to a hazy problem.
(And by "hazy problem" here I basically mean that Theranos is pursuing something that sounds like a problem (medical testing) but is actually a large number of only somewhat related problems. For me, going after a known problem would have been picking one test, or a small number of them and then nailing that before expanding to adjacent problems.)
The difference is between implementation/engineering, which is what most software companies are doing, and invention/science, which is what Theranos is trying to do. It's OK not to build something before selling it if you know that it's possible to make it, but just haven't done it yet because it would take time/money you don't have. It's not OK if you don't even know if it's possible.
(And by "hazy problem" here I basically mean that Theranos is pursuing something that sounds like a problem (medical testing) but is actually a large number of only somewhat related problems. For me, going after a known problem would have been picking one test, or a small number of them and then nailing that before expanding to adjacent problems.)