What is the incentive to use bitcoin due to transaction fees? Apologies for any naivety in the question, as my understanding of the subject is still basic.

My understanding is that once all the coins have been mined, the incentive for miners comes solely from client transaction fees. When that happens, why would someone choose to use bitcoin and pay a transaction fee over fiat currency without a fee?

Does this mean bitcoin is fundamentally infeasible as a general use form of currency? If so, what are the specific use cases that make it more appealing, even with the necessity of transaction fees? If not, what would compel general use adoption?
There are two scenarios we could see as the block subsidy (inflation) halves every ~4 years:


The number of fee-paying transactions increase per block whilst median next-block fee remains low/negligible
The fee per on-chain transaction increases


We are currently seeing scenario 2 play out, where most user transactions are expected to take place off-chain. Transactions that are made on-chain are expected to be settlements of many off-chain transactions, likely collecting a large number of smaller fees within.

Both scenarios are fueled mostly by adoption of the network, and until the subsidy is gone (zero inflation), increases in coin price will help to sustain miner incentive.