The argument is again and again that the value of Bitcoin will increase because supply is limited to 21 million. But this is quite simply wrong. Every time Bitcoin is forked that is in real terms an expansion of the Bitcoin currency beyond 21 million. To some degree the same is true of alternative crypto currencies which will flood the market. There is already more than 1000 cryptocurrencues ( https://en.wikipedia.org/wiki/List_of_cryptocurrencies )
Th forking (or absence of it) does not effect Bitcoin's supply. At best, you can consider it as a "gift" to all bitcoin holders, which will increase the overall worth. It in no way impacts the overall supply of 21 Mn, which is set in stone.
But I am sure that Bitcoin is not such a coin 