BTC's longterm security depends on people paying extremely high TX fees which won't happen in a free market.
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Is there a gaping hole in this argument?
What's an extremely high fee? What's high for you may be low for someone else.
In 2019 the average fee was around $1
In 2021 it was $2. In 2023 it went up a bit again, but stayed around $2.5.
I don't count extremes where due to congestion it skyrocketed above $20, which happened in 2018, 2021 and 2024.
What makes you think the fee will be much higher in the coming years? The history points towards a slow and gradual increase. You can still send a $2 tx if you want and it will go through.