Here's my math involving 8 billion people:

If we assume 7000 tx's per block, then the 144 daily blocks gives 1 million transactions. Most blocks will have less than 7k tx's, but let's go with this high tx figure for now just to explore the math.

If we divide 8 billion people by 365 million tx's per year, we arrive at almost 22 years per tx in terms of bandwidth, which impacts the tx fees.

Granted, a certain percentage of the world's population are children who will not need to spend from a savings UTXO on L1. Then there may be a certain percentage that don't use Bitcoin at all. Finally there are hodlers that have a 5, 10 or 15 years horizon for their savings.

If I am optimistic, 1 L1 tx every 10 years should be affordable for most people, so that leaves L1 as primarily a savings layer, while L2-L3 offers cash functions via decentralized banks/nodes.