They failed at step 1...
They failed at step 1... make paying less hassle than recovering from backups.
For Randsomware to be effective, the price needs to be about £50. That's the amount most people would pay in the hope of getting their data back. When you get beyond that it becomes less and less likely they will pay. Technical-ish people will have backups, non-technical people will trash the Malware and make the files unrecoverable trying to fix it. On top of this, the more you demand, greater the chances of law enforcement becoming involved.
Essentially they need to target a price-point that is about the same as a years licence to a quality anti-virus/anti-malware suite.
At £50, if people are reasonably sure they will get their files back, they will just pay.