[UncleMeat]

There are two kinds of rarity. There is rarity of the thing itself and rarity of things like the thing. Consider an extremely rare thing used for some industrial application. It is very expensive because there is little supply. But if there is another thing that functions just as well then the price of the first thing drops, even though the supply of that thing is fixed.

The only differences between bitcoin and bitcoin2 after a fork are the miners. If the number of miners is sufficiently large to be confident in transactions, original bitcoins and bitcoin2s are just as good at being used for whatever. This is even worse if bitcoin2 has some new desirable properties that bitcoin does not have.

[Klathmon]

I agree to some point. You can't forget the network effect, which in many cases is the most important factor (it's easy to make a clone of twitter, but good luck getting everyone to switch). Because Bitcoin is basically just a way to ensure that a group of people are doing math with a given set of rules, if you get a copy with slightly different rules, you need that group to agree to them to give it value. It doesn't really have many analogies in the physical world that I can think of, the closest is actual physical currencies.

Just because I can make a "Flollar" doesn't mean that it's going to take a bite out of USD. I have nothing to backup my flollar, no users, no army, nothing. It's the same way with cryptocurrencies. Just because you can fork bitcoin doesn't mean you'll take a chunk of it's value. You still need to provide all of the other things that make bitcoin valuable that's not in the codebase (decentralization, userbase, vendors/exchanges, software that works with it, time with real usage to show that it's secure (or at least that your changes are secure), and just trust that it will stand the test of time). And even if you do that, bitcoin can and will evolve over time. If you start to eat bitcoin's lunch, there is no reason why they can't just fold your changes into bitcoin proper. If it's in everyone's best interest to have the feature, then consensus will be easy to achieve and the network can be upgraded. In a way, it's similar to forks of an open source project. In the vast majority of cases, a fork of a codebase doesn't reduce the number of users of a project. In some cases it does, but it normally doesn't happen overnight, and takes years and years to have people transition over (take openoffice vs libreoffice for example).

All that being said, I do think that bitcoin is in a bad place right now, and they are dangerously close to allowing another currency to jump up as the main contender, but I don't believe that any of the top 10 or so have actually solved the scaling problem that bitcoin currently has without getting rid of the biggest benefits of a cryptocurrency.