Market cap is not that important, I agree on that. While Bitcoin went to all time highs in January 2018, it was actually Ethereum that caused it to go to that price of 20k. This is because of the ICO bubble, it inflated the value of the entire market.

As for a store of value, well, I do subscribe to the thinking many people have that there is no such thing as intrinsic value. So, a store of value, in many respects, is merely an imagined value within the mind of the person storing it.

I do believe in intrinsic value, but the only things that truly have intrinsic value are the things that we need for actual survival. Although water is not highly valued in a city, but greatly valued in a desert, it does have a base intrinsic value. We need clean, drinkable water, regardless where we are.

Gold and cryptocurrencies are not things that can have intrinsic value, because they are not essential to our physical survival in any direct sense. However, they do have a subjective value in the same way baseball cards have a subjective value. As long as someone is likely to care about the item, it can become a store of value.

Bitcoin is actually terrible gold. Everything gold is good at Bitcoin is terrible at, but Bitcoin has one special use that gold is terrible at: teleportation.

Bitcoin can teleport from my wallet to yours in 10 minutes. It doesn't matter where you are, I can send you money you may need. This is valuable in many situations, and for this reason, there is likely going to remain someone interested in dealing with you in cryptocurrency for years to come.