The concept of rich-get-richer is an application of the preferential attachment. In a sense, it's the seniority of the first-comers. Because the first-comers have been in the network for longer, it's more likely that they have more chance of being linked. While the chance of being linked is high, that means they will most likely be heavily linked. Following the preferential attachment law, they are more likely to be linked too. As new nodes join the network, these heavily linked nodes will be linked more and more and become a hub. The idea behind the fit-get-richer concept is not much different from the rich-get-richer except that it's the latecomers that become the hub. The latecomers pass the pioneers to become bigger hubs. The example of that would be google. As the most popular search engine, google has more customers than yahoo or AltaVista. (I remember back in the days, AltaVista was really hot at one point.) maybe the special characteristic of newcomers actually can surpass the preferential attachment. We can also look at fit-get-richer relating to the other phenomenon relating to a real network. Real networks are more complex than scale-free network even though scale-free model does illustrate better than random network. There are other mechanisms such as againg (which relate to retirement), node losing attracitions to others, or the age of the nodes. By evaluating other mechanisms that scale-free network ceases to illustrate, we can understand that fit-get-richer is actually an inevitable phenomenon for all the hubs at some point.
