You are confusing "healthy" (ie positive-sum) competition among consensus-critical blockchains with unhealthy zero/negative-sum contention within a single consensus-critical blockchain.

Altcoins are Bitcoin's healthy competition.  If Bitcoin isn't competitive we'll use Litecoin, Primecoin, and Monero instead.

Classic and other XT-like governance coup attempts are declarations of a war that only one side can win.