It’s weird in that most users would value it at $3.99 a month, but the average user also scrolls for several hours a month, with each one of those hours packed with ads.
This equates to way more than $4 in revenue a month.
Visa takes a cut from transaction, only a portion of that goes to the bank. I get 2.5% cash back on my transactions, but Visa only charges a 2.24% transaction fee. There must be more to cash back than the transaction fee.