Wow, I never expected so many replies. I really appreciate everyone providing such thoughtful comments and staying on topic. Great to see this forum is still so active; reminds me of the early bitcoin days. I think I'll be posting more often here. I'll try to address some of the replies in this post:

@Casdinyard
> The question is "How do you define a currency's success?"

Something is successful as a currency if those who are selling goods and services prefer to accept it and hold it until they can also use it as payment. If many potential customers are holding it, a merchant will accept it. But the merchant will only hold it if the price is stable. Otherwise the merchant would risk not being able to pay suppliers. So when merchants accept bitcoin they immediately convert it to fiat. So by this definition my original post is asking when and if ever we will reach a point where merchants will not only accept bitcoin, but hold it knowing they can use it to pay their expenses and suppliers.

@Silberman
> Most of that volatility is created by incoming money. Once the market is mature enough and the incoming money is a tiny fraction of the money already present then we could begin to see bitcoin flourishing as  a currency.

Very well said. However, bitcoin is still an experiment and we have yet to see how people will perceive it when the incoming money dries up. Will price stabilize or will it implode. I don't think it will ever implode to zero since it has a production cost. It may stabilize, but still go up or down in value based on the population size holding bitcoin. If there are twice as many people as before, each can have 1/2 as much bitcoin as before and the cost of a hair cut would have to be 1/2 as much. But this would be a very gradual change when the population size holding bitcoin is everyone in the world.

@Mauser
> The demand for bitcoins is growing every year and we are seeing a higher number of institutional investors from around the world to switch into the crypto world. With all these new players the pressure on FIAT currencies will rise too.

That's actually a bit scary. Bitcoin may trigger the collapse of fiat currencies (as everyone rushes to convert fiat to bitcoin), while it has not yet matured to the point of being stable. So we could have a period of time when people are not sure what to use as yardstick for value.