This is the same conclusion I came to. Bitcoin's incentive structure makes sense if the users of it gain value by being able to use it as a common medium of exchange. If you look at the money that e.g. mastercard and visa pull in, it makes sense that you could sustain bitcoin off of that indefinitely. It could also conceivable result in a relatively lower market cap if people do not in fact save money in bitcoin, reducing the threat of 51% attacks. As a store of value, the incentives no longer make sense: for the 'store of value', it must be deflationary, thus mining cannot produce new coins indefinitely. But it also cannot be too expensive: if just keeping your coins requires paying a significant percentage of the value of them to secure them on an ongoing basis, you're ultimately losing in just the same way as someone in an inflationary coin does. There's also no particular mechanism which makes sure said price is actually correct: ultimately you need to figure out how much mining is 'enough', and also realistically have some mechanism to spread those costs out evenly amongst holders of bitcoin, lest it become a tragedy of the commons where no-one wants to contribute.