Due to wealth inequality, we assume that majority of the crypto investment would be from ultra-rich. It might become quite normal for them to invest 1% of their wealth in crypto for uncorrelated diversification. In a way this is very similar to buying art which probably doesn't have much utility except among other wealthy people as socially agreed upon store of value. These folks have estimated wealth of $10T so that puts market cap contribution from them to $1T. Let's assume same amount comes from non-ultra-rich investors. So we can estimate btc market cap to $2T. This puts reasonable eventual upper bound value of 1 btc to $95,000. This eventual value might never be reached however because all 21M coins never be mined, not all wealthy people might do this, and also other coins will fragment the market. May be 3/4 discount is reasonable at this point to accommodate these factors which might put the value to $25K at this point. This is obviously assuming no black swan events like countries making it illegal or some other virtual currency tech doesn't become popular.