If it can only rise then why is it often dropping? There are no guarantees in this social experiment. I believe it has a future. But my opinion plus a cup of coffee equals... a cup of coffee.
To quote Albert Einstein: "as far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality."
In reality, there are a lot of factors to consider. Market manipulations. Human fear and stupidity. Unawareness. Computer glitches and human errors. etc.
But if you truly understand the mechanism behind Bitcoin as a cryptocurrency, you would be baffled as well as to why there can be drops in its price when it should be linearly increasing in an ideal, purely mathematical and logical world