The question you're really asking is: How do you value a network.

The answer is known as Metcalfes Law, which is V ~= n^2 (ie. Value of the network is approx number of Nodes raised to power of 2).

This means that a network with 200 users isn't twice as powerful as a network with a 100 users...its 4x as powerful.

Point being, increasing bitcoiners increases the value of the network at an exponential rate.