If it's about record-keeping, why do I need 1BTC? Doesn't 0.1BTC keep the record just as perfectly?
Discussion
You need to pay a fee to write new records, so you need to spend whatever the current fee rate per byte of data is. It’s an open global market, but the space in the next block is finite.
Once written, the record does ride free and the security/immutability comes from new records continuing to be written.