Only bitcoiners consider bubble/P&D cycles as "natural behaviour and growth of a promising investment".
Only Trader cultists compare Bitcoin to stocks, penny or otherwise.
I don't see why not.
It's an asset that can be traded and is subject to supply/demand dynamics
like any other asset.
Every chart tells you a story, and the all time bitcoin chart and his bubble cycles tell you something ugly.
I suppose if you treat Bitcoin as a mere asset, it's easy to think of it as some kind of tradeable commodity, rather than disruptive technology. Bitcoin the disruptive technology is much more than bitcoins, the commodity though.
If Bitcoin
were an enterprise, its IPO would still be years away. Of course the charts look ugly compared established commodities like metals, agricultural products or foreign currencies, or publicly traded shares of the kind of established businesses whose shares are already traded on exchanges. The wild "bubble"-like price fluctuations are typical of new enterprises still in the domain of angels and VCs. By the time most new endeavors reach the point of public offerings, the bumps have been smoothed out.