We cannot blame people on how are they using Bitcoin whether it is for investment or currency purposes. What matters is that Bitcoin grows as a cryptocirrency both in value and popularity. Many people are taking advantage of its volatile market price and there's nothing wrong with that. On the other hand, many countries are still not widely accepting Bitcoin as a mode of payment, so what's their choice then? Would it be better if they will just wait for its adoption? Ask yourself as well, are you using cryptocurrencies on most of your transactions? With high fees?
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It is the choice of people to want to use bitcoin as their transaction or as their investment/trading, and both of these things will not make bitcoin deviate from its intended purpose, because it is the same as when people trade fiat on forex, it will not deviate from the purpose of fiat as a transaction tool. So this does not need to be too much of a problem, because it is as simple as people want to seek profit on the increase and decrease of the price of bitcoin and there is nothing wrong with that.