I could play roulette 5 times putting my bet on red each time. This could win me a lot of money or lose me a lot of money or come close to even.
If I play roulette 5000 times putting my bet on red each time I will more closely get the result of being down 1-2% as the house advantage dictates.
If I buy and spend bitcoin every day/week for several years the result will be a slow climb as bitcoin is a depreciating currency.
So no, bitcoin is not only suitable as a store of value.
Yes, but how many people want to suck up the variance of 100% swings in a day just because they know they may make money long term? Even that is far far far from certain. Another cryptocurrency comes up, a blockchain fork occurs, etc etc etc.