But without some incentive to do so, they won't. If they're already getting around basically one of the biggest dealbreakers for the Free tier (the ads), then there isn't really incentive to pay 9.99 a month when they're already getting essentially the same service for free.

Plenty of businesses don't give away free samples, and survive fine.

Obviously Spotify sees value in offering a free tier to their service.

Yes, the value is that they make money from it through ads.

*most businesses.