1. What definition of "bubble" do you use? (link?) I guess there are different views on what a bubble is and whether prices have to go down to zero in succession.
2. I think the Gartner model fits almost perfectly (to this point in time) and will provide guidance in the future as well should fundamentals change (as they most likely will, --> see wordpress.com).
This wikipedia entry is illuminating -
https://en.wikipedia.org/wiki/Stock_market_bubble Especially if you draw a straight line under either the NASDAQ or Nikkei index for the pre-rally prices preceding the dot-com bubble. Prices inflate, reach a euphoric peak, then decline to previous levels.
There are exceptions where the 'previous level' ends up being a complete lack of confidence in the investment itself, so is manifested by a zero price valuation, but those are fairly rare. You do see this kind of behavior in thinly traded issues like 'pink sheet' penny stocks and other highly speculative investments.
That is why I say we're not in any bubble, or have been, because we would be trading around the inception price of bitcoin -- or at zero.
We most certainly have had run-ups and blow off peaks, but you get those in commodities and other markets as well. Such as the summer run-up of wheat during the severe drought in the USA.
I have no issue with the Gartner model, just that correlating it to price movement doesn't make any sense. It is meant as a general representation versus a literal one - ie., you can't say we start at 0.25, swing up to 40, then stay at 12 forever on a gradual up-slope.