mcbain's comment that I am replying to,
https://news.ycombinator.com/item?id=20981242 , is referring to the NYTimes story on $1B in transfers.
Those substantial transfers ($1B) were a decade ago.
The sentence you quote does not appear in the NYTimes piece and is, in comparison, peanuts. I do not have access to the Bloomberg piece for full context, but the sentence you quote does not say the movements were self-payments from Purdue rather than just personal transfers between personal accounts. It also does not say all $20M was in 2018; there could be a $1k wire in 2018 for all we know from the single sentence.