a very good point and i completely agree with it.

but it doesn't have to be only one. you can do both. you can use bitcoin as a currency but also have it as an investment. for example you buy bitcoin today at $1 to be able to spend it as a currency when it is  worth $2 which satisfies both investment and currency aspect of it.

the price rise, the volatility that comes with it and the fact that people will use it as an investment is inevitable.