Even more impressive than the market cap previously referenced is their actual business is vastly superior to Spotify.

Sirius 2019: $7.8b in sales, $1.7b operating income

Spotify 2019: $6.7b in sales, -$73m operating income

Spotify's market cap is supported by a fantasy that one day, somehow, if they get big enough they might generate a real profit to support their Wile E. Coyote valuation (don't look down). So for example, if they get to $20 billion in sales (in another 10 years), maybe they'll spit off as much profit as Sirius does right now in exchange for a similar market cap.