My understanding of this is that you have a highway and a road (with a low speed limit). The highway gets congested if many people use it so they’ll all move slower. If everyone takes the highway, it’ll still be faster than the road, so everyone chooses to take the highway. On the other hand, if everyone spends half their time on the highway and the other half on the road, all of them will be able to travel faster (But there is no incentive to do so).<p>At Nash equilibrium, the highway is over-utilised while the road is under-utilised. So stripped to the core, this is an example of tragedy of the commons where if every single individual works for their sole interest, they will all lose out and yet nobody has an incentive to make a change.