One problem I see with the store of value idea, in the long run, is that I don't know if BTC's double spend prevention will survive its design.
The point of mining is to prevent double spend attacks. It does this in a rather brute-force way: the network as a whole always maintains a higher hashrate than any attacker. The network always out-spends the attacker to maintain security. As described in my prior comment the funding for this massive hashrate comes from newly generated BTC.
But Bitcoin is designed to wean itself off of emitting new coins as a mining reward. This is done by halving the block reward arbitrarily every 4 years. This is necessary to fulfill the promise that there will only ever be 21M coins, which has been a huge selling point to anti-inflation investors.
Ultimately the mining is supposed to be funded entirely by fees. But there is no market mechanism to ensure that fees "make up for" the lost emissions of new coins. The only reason to pay a high transaction fee is if there is high transaction volume, causing blocks to fill up, so you are competing for space with other people trying to make transactions. If transaction volume is fairly low, fees remain low. You can see fees only become a meaningful part of the reward at times of unusually high volume[0].
So, it seems plausible to me that if Bitcoin mining was funded entirely on transaction fees, the total mining reward would not be high enough to sustain enough hashrate to be impervious to 51% by a powerful attacker. That's especially true if most users are holding onto BTC as a store of value not attempting to transact in it. As far as I know, there is no successful cryptocurrency that functions using fees alone. Bitcoin is in a very slow march towards being the first to do that.
Basically the network is currently funded with a "tax" on holders of BTC -- newly generated coins dilute the value of held coins. This to me makes a lot of sense for a store-of-value. But the coin is trying to transition to funding security with a "tax" on users of BTC. Nobody really knows whether this will work. In fact nobody knows how much is the "correct" amount for the network to spend on mining at all. All we know is that with the current level of spending we haven't had a 51% attack yet. Are we spending 2x more than needed? 10x? 100x? It's impossible to say but the design of BTC seems like a slowwwww experiment to find the level at which it fails.
[0]https://charts.bitbo.io/fees-percent-of-reward/