1 simple format and they are up an running like nothing happened. I think a lot of businesses and personal users should use the backup a lot nowadays because of the risk of ransomware if they think that their files are precious. A external HDD or a cloud storage would save them from different type of ransomwares.
I heard there are ransomwares that are sort of delayed action to frustrate you that even if you made backups, you don't know if those are infected as well, since they don't immediately lock down your files. Ah criminals, always ahead of everyone.
It is wrong, they don't target only large corporations although that maybe their primary goal. Bitcoin users usually are not large corporations but individuals like you and me who keep their bitcoins in their PC.
Guess you can compare this to counterfeiting money. Larger denominations would earn you more, while smaller denominations might not even be noticed. With bitcoin users, the really large ones would cause an alarm when hacked, while the really small ones are not worth the effort. It's about finding the Goldilocks zone.