Their actual financial investment in the company was likely nominal if anything at all. Spotify likely offered an ownership stake as an incentive to get the labels to take a chance on an unknown company and an unproven model.
Whether Spotify goes public or not the labels have already made out very handsomely was my point. That's the $5 billion that Spotify often states that it has paid out to rights holders. So yes it very much has borne fruit, $5 billion worth. If the company goes public its basically gravy for them.
The record labels were decimated back in 2006/2007 when Spotify started. Things looked pretty bleak for the industry as a whole. So yes the labels needed to do something as their revenues has pretty much dried up comparatively to a decade earlier.
