This is a fair enough argument but some goods and services you can only pay for via fiat. In fact most goods/services can only be paid for by fiat or credit. Inflation is going to be a thing at all if you are just selling the amount of BTC you need to make a purchase in fiat. I am guessing you mean exchanging for large amounts of fiat that you wouldn't be using in a few days time.
I agree. Although the recognition and potential of bitcoin is steadily on the rise. What is the sense of earning bitcoin without any purpose for it. There are so many other things you can do to utilize your bitcoin better. You can either invest it in a good company, or you can trade them in the market. Another venture you can do is to trade it off to cash and use it to build a business to pair off with your bitcoin earnings. I think the essence of a currency is to be used.