It's very much like the Linux Desktop - it exists, some people love it, it's never going to disappear, but it is very much a niche interest that will never be mainstream, for a multitude of reasons.

Also it hasn't gone up consistently, it's still at around 50% of its peak almost two years ago.

Any asset that doesn't crash back to a penny likewise goes up astronomically from the day trackable value is first created. Bitcoin's chart appears to have outperformed the market so dramatically, percentage-wise, because its chart tracks price from effectively zero (depending on how you would price a 1/10000th slice of pizza) or a dozen or so pennies (if you're starting from the first BTC-E numbers). But this is really not any different from what happens to shares in a private company, which also start at effectively zero as well.

Publicly-traded share values aren't visible to the public until they have already risen a hundredfold or more from their inception (in terms of percentage gains). Sure, Bitcoin was visible to "the public" but only if you happened to be in the right place at the right time and knew the right people - which in practice are opportune circumstances no different than those available to people who happen to be close to the founders of a privately owned company.

No, it hasn't, unless you've got some sort of alternative definition of "consistently".