It's not just to send value, it's to hold value. In other words Bitcoin is an asset thats primary use does not have to be as a medium of exchange for accessing the blockchain as a payment rail.
The amount of USD or sats that are sent daily shows how much interest the participants have in that use
The amount of USD is different from the amount of sats that are sent daily, they are not interchangeable as your usage of the word "or" would imply. If each sat were worth $100 one day and each transaction would send thousands of sats, does that show less demand than today where people still send sizable denominations of Bitcoin?
There are also more ways to transact using Bitcoin than only making on-chain transaction (see the lightning network). And, to the chagrin of some who thought there would only be monetary use-cases for the Bitcoin blockchain, there are also people who use the blockchain for its immutable properties (see ordinals and inscriptions). These allow for individuals to make low value transactions with high fees (in which case dollar amounts would be a poor metric for measurement).