"under 1 BTC" means nothing if you don't account for bitcoins price. The 50, 25 and 12,5 BTC block rewards of the first epochs could buy a lot less than todays 6.25 BTC reward.
Unless you are assuming Bitcoin has already become a unit of account in the next few years its a bit speculative to assume 1 BTC will be worth less than 6,25 BTC now.
Not assuming any price value for btc in 9 years, because nobody knows. I am assuming that the security model will change. And in 13 years the subsidy will be ~40 sats/vbyte then 20 then 10, then 5. The challenge is still to prevent reorgs and network splits.
So you’re assuming hash power will drop because it won’t be economically feasible for miners? That IS assuming price value.
But yeah, I get what you’re saying.
You can reverse the thinking. Instead of thinking that an increased price increases the security, you can think that a robust security model increases the ceiling on the price.
The only reason miners spend so much energy is because it's profitable to do so.
The only way security leads price (and this is bound to happen a little bit) is if people actually base their investment decisions on hashrate.
Maybe institutional investors think this way? They obviously will want to be sure their investment is safe.
As far as I can tell, however, the block reward plus fees multiplied by price determines the security budget, which determines security, at least in the medium to long term.
And for now, because the block reward makes up the bulk of miner revenue and is completely predictable, the price of BTC makes a much larger difference in security budget than fees do, especially when fees in sat terms can go down when the price goes up.
