There are many outlier things that are only of a certain value because some group of people decide that they are: art, baseball cards, collectible postage stamps, brand label clothing goods ($3,000 purses or shoes), venture capital valuations, and so on.
Why is a new Ferrari so expensive? Ferrari could manufacture a lot more cars if they wanted to. They could also charge less, their margins are tremendous. It's an obvious function of supply and demand. The price is so high because people say it's worth paying that. It's that simple. If all of their customers suddenly decided it wasn't worth paying that, Ferrari would either lower their prices or go out of business.
Even bond ratings are often open to significant subjectivism that can swing their value considerably.
If enough people decide that a Bitcoin is worth $100,000, then that is what they will be worth. That is in fact how most things in the world are valued. Bitcoin's scarcity and the fact that in the near future it will become almost impossible to mine new coins, adds to the premise.
The question is: does Bitcoin's low utility value and ease of trading in proportion to its market cap, particularly open it up to dramatic whims of the mob? Yes, which you see in its volatility. That won't change until or unless it finds greater baselining usefulness.
Ferrari cars charge a premium, much like Apple does but they are a hell of a lot faster than a Honda Civic. Baseball cards started as a thing outside of rarity, they had information and a picture which was more valuable pre Internet.
Now you can argue that Antiques should not gain value from age, but old junk is not valueable, old pristine stuff is. So your argument is people overvalue something they have a rational reason to value, which is different than placing clause on something without inherent value.
I am not saying Bitcoins shpuld be worth zero today, I am saying they will be worth zero in 100 years after the fad ends unless they fix the inherent problems with the protocol so it can be used as a medium of exchange.
No, the 22+$ transaction fees are the problem. People are saying that it's no longer a currency because of them, but that just makes it a security. IMO it's currency or scam not currency or security, because there is no inherent value beyond currency.
It's become a scam because of the incentive structure. The miners control the currency and are trying to maximize the money they extract not grow the usage of Bitcoin.