These scams work on a large enough fraction of people that it's worth the scammer's time to send them out. If a scam is really hard to believe (e.g, the "Nigerian prince" scam) but you can send out say 10 million messages in a mass emailing, even if one in 10,000 falls for it and sends them $100, that's $100k for a single email.

When it takes more time and effort per attempt, it needs to be more beliveable, like this one you describe. Here, working on people's stress and fear, they might get say 5 out of 100 to give up enough info that the scammer may get $1000 on average from each. If they can send out 500 such payment requests in an hour, they may $25k for that hour of effort.

I recently was hit by a different sort of scam attempt, trying to get me to send an Amazon gift card to the scammer: https://medium.com/crows-feet/would-you-fall-for-this-sneaky-little-gift-card-scam-7c727de9a37d.

I didn't fall for it, but they used social engineering that might have worked on many less suspicious people.