If it does become a long-term trusted store of value, BTC should trade around $2,000,000 a coin (depending on how many coins are lost and are actually in circulation). That is over 100x the price of where BTC is today.
If BTC does not become a long-term trusted store of value, its likely price will be close to zero (unless it becomes a "cool" collectible... which is a possibility).
So if you think BTC has a 10% chance of becoming a long-term trusted store of value, it is a good investment with a nice expected return. It is still very risky but professional investors should invest some small portion of their portfolio in this case.
I think you somewhat misunderstand what the idea of a store of value means in practice. As the term itself suggests, a store of value is about keeping, i.e. not losing value over the long term. It doesn't mean any specific price. In fact, it may mean any price as well as a change in that price. For example, gold is considered a good store of value even though its price is volatile (though not as volatile as Bitcoin's, of course). How come? The answer is simple, it is its price in dollars (or whatever) which changes, not its real value as it is valued against other non-monetary items. In other words, it is the dollar value which fluctuates and makes it look like gold is volatile, while in reality gold is pretty stable or even rock-solid
Now you can apply this logic to Bitcoin and see how well your theory fits in