Incentives matter, and if the ransomeware developers are actually getting paid a lot, they will continue exploiting these vulnerabilities. On the other hand, if it turns out people don't actually bother paying despite being locked out of their computers, would the hackers even bother continuing this line of attack?
Perhaps a ransomware/malware criminal reading this can make a throwaway and provide a better estimate.
So I bet their plan was to infect as many as possible over the weekend, and see money roll in come Monday once the Business Decision makers are in play and IT has had time to say "Yea our backups are fucked so we either pay or lose all data"
Lots of money might pour in on Monday as those infected decide that paying the ransom maximizes business continuity.
Already has, twice
Depends on where they live. For most people on Earth this is a very large sum of money that will go a long way (just not 'here' in the countries where the virus spread).