I'm playing Devil's advocate and not justifying or defending their fraud and the physical harm they caused, but if we were to look at Holmes' intentions, I'm suspecting it was something like "we just need to do this for a few months/years until our technology works", rather than "let's just run this scam forever and get rich". As for how close they actually were to developing that technology (and assuming most of their talent didn't leave) or if it was even possible for them, who knows. And of course, regardless, they still intended to commit fraud and should pay the price.