Fundamentally, the value of anything is a function of its supply and demand, even currencies. In Bitcoin's case, the demand derives from the new utility provided by a unique and clever solution to the problem of distributed consensus among untrusted parties. Eg, people want to transact and neither trust each other to deal honestly nor trust a central monetary authority (either not to devalue the medium of exchange, or not track them, etc).
Bitcoin created a system to make that possible, and hence has demand (and limited supply) and value. As long as the underlying reasons for that demand don't vanish, it should always have some value.
The question is, can forks of Bitcoin provide that utility in a significantly better way, that gives them enough marginal demand over Bitcoin to incentivize most people in the Bitcoin network to switch? Same as the general competing currencies idea espoused by Ron Paul and others (for the record, I'm a skeptic, but find the idea interesting), just applied to virtual P2P currencies that are created by hackers rather than nation states (of course, there's nothing stopping a nation state from creating one either except their own laws, mindset, and momentum).
As for early adopters being favored, you can only make that observation with the benefit of hindsight. Had bitcoin failed early or never taken off, early adopters would have lost. The expected value back when early adopters decided to commit and mine and accumulate bitcoin is decidedly different from the realized value of bitcoin now.
Also, most currencies favor early adopters, even (especially) gold and silver. I don't think that's really anything new.