Justifiably, any attribute or factor that is known to be influencing prices, is doing so as it leads to demand. On how easy basis of such factor demand is raised and thus the price. Hence, these domains of media like segments as you say like http://www.hindi.media gain worth from the same factors that lead to demand. When price is enhanced or goes premium, the domains are thus known as premium domains.
You can turn then into content sites, set up an actual website, or try to sell that site elsewhere. You may even luck out by selling a site that's up and running and full of great content already. In this case, you can ask a higher price. Or, you can set up a shared hosting or direct hosting website. Shared hosting and direct hosting websites can be profitable too.
The domain name industry is quite similar to the real estate industry in a lot of aspects. There are end users, brokers, consultants and domain flippers or “domainers”. Domain flipping works similarly to buying a house, renovating it (or even sometimes just sitting on it) and then selling it again at a higher price point. The gist of it is: you’re purchasing a domain name and betting it’s worth (or will be worth) more than you paid for it. If you’re right, you get a nice paycheck and move on. Those who make a living out of this just rinse, repeat, and scale.