Who buys a pile of old songs for hundreds of millions, and what do they understand that most artists don't?

The headlines keep landing: another song catalogue sold for hundreds of millions. The artist's name is familiar but the songs are decades old.

For an adviser, the right reaction is not awe but curiosity, what is actually being priced?

The answer turns out to have almost nothing to do with music, and almost everything to do with what streaming quietly did to royalty income.