# Superconductivity as a macroscopic phenomena

I have been doing some reading on the formulation of BCS superconductivity. From what I understand, an additional non-vanishing term $$\Delta c_{\uparrow,k}c_{\downarrow,-k} + c.c$$ develops below the critical temperature resulting in electrons pairing up as Cooper pairs. What is however not clear to me how this results in a macroscopic quantum phenomena. Is the macroscopic nature due to pairing of electrons with positive and negative momenta and that that there are multitude of such states around Fermi level that satisfy the criterion that the net momentum of the pair be zero ?