Onus :
There is no inherent requirement for a "bubble" to cryptocurrency. Any asset, whether real or virtual, can experience bubbles.
What will keep the hashing networks operating is the tiny transaction fees that are included; the miners collect those fees when they process transaction hashes in addition to the new coins they generate from "mining."
As to whether or not it should be taxed, of course the parasites want to be able to get their hands on anything of value. The untraceable, decentralized nature of cryptocurrency transactions however does offer some protection from these would-be looters, and is one of the advantages of cryptocurrency.
... And probably also one of the reasons why it could potentially hold it's value in the long run since it's practically untraceable. Making it the perfect currency to do illegal trading on the web, thus why I also think it's inevitable that it will be regulated by authorities if the currency keeps getting more and more established.
The stock market is not hard to understand since it's essentially comes down to supply and demand. The trick is to predict the demand before it actually exist, thus making the market really abstract in some cases since a prediction of a demand can end up being a self forfilled prophecy and the other way around, thus affecting the stock value with no real reason.