Simple fact. If it doesn't have use then it's not really much better than any current centralized paper system. Why? Well there are many reasons.
Lets start with how it's stored. If it's stored on an exchange well all you really have is a login to access it that can disappear at any time. The old saying "Not your keys, not your coins". You don't even have a bank or exchange statement showing your balances and account numbers. At least if you have other instruments on an exchange or in a bank they are probably partially if not totally insured if something happens to that institution. If you move it off the exchange into your own wallet then well how do you use it? If it's not meant to be spent you have to go right back though those same centralized exchanges to convert to something that can be used. Same thing you have to do with stocks, bonds, and other financial instruments that already exist.
Well people are going to argue that you control it. Well you might own the keys but you don't have the power to move the coins. If the network is congested it's a crap shoot. Need to sell some BTC to pay the rent? Better pay a damn high fee or hope it doesn't get stuck in the mempool until after your evicted. Then there is where do you convert it to something usable? Again you have centralized exchanges. With full blocks and RBF in play in person doesn't work unless you both want to wait who knows how long for it to confirm. So what about decentralized exchanges? With full blocks they don't work either. Price fluctuates too much. Think your are trading at .1 BTC at $9000? Well by the time it goes though you might only get $850 to pay that $900 rent. Less after fees. At least if I own a $9000 certificate or bond I can trade it for it's face value and know what I'm getting. Stocks not so much but unless it's something with little volume your trade will probable execute faster than a BTC transaction.
Next they will say well just use Lightning Network. Yea right. Still have to wait for that TX to open the channel. Think $900 will ever route? I don't since LN was only designed for transaction under about $40 and even with that it still needs at least 133 meg blocks.
So as a store of value all you can really do with it is buy and sell it. Nearly all of this will need to be done though centralized services. The same type of services that already existed for other financial instruments. When you do this your coins become nothing but numbers in a database. You aren't trading BTC you are trading IOUs. At that point you don't even know if the coins really exist or are just made up numbers being tossed around by programs. No better than any other instrument at this point.
As long as BTC is intended to only be a store of value it has no real security. The security doesn't come from POW. Sure POW secures the blockchain but no matter how much hardware is securing it if you can't get your TX into a block POW means nothing to you. Use secures the coins. If you can't use an exchange to convert your coins you can trade them in person. Even better you can actually use them to buy stuff directly or pay people to do jobs just like cash. You know cash that centralized issued paper. Seems it's more useful than BTC as store of value too.
So without utility what good is BTC as an unreliable store of value that you may not be able to access when you need it? Utility gives value. People will eventually wake up to that fact.