Given that others in the band were already doing so, makes sense:
Mick Fleetwood has sold his rights to hit songs including Go Your Own Way and Dreams to music publisher BMG, becoming the third member of Fleetwood Mac to strike a lucrative music deal in recent months.
Fleetwood, who co-founded the band in the 1960s, has sold the publishing and recording rights to the royalties from more than 300 tracks from hit albums including Fleetwood Mac, Rumours and Tango in The Night for an undisclosed sum.
Depending on which rights they are they last up to 70 years after his death. Why not take a lump sum now rather than an annuity for the great grandchildren?
One thing that Stevie Nicks said though. The reason Fleetwood kept going bankrupt was because he tried to keep up with the spending of the other members of the band. But as he didn’t – or rarely – write songs he earned significantly less. So, largely, these are mechanical rights, not song rights, being bought.