There are indeed many clones of Bitcoin. Look here at https://www.coingecko.com/

Those stats determine where most of the resources have been focused on. Each coins have their own agenda, goal, and different group of community backing it.

i think its a bit different b/c ethereum is supposedly useful as the 'fuel that allows apps to utilize the concept of a blockchain' in apps.

i suppose the idea is that it 'burns' ethereum to run an app on top of it, so I can see a scenario where ethereum becomes too expensive and businesses that use decide to move to a different fork that is less expensive.

I guess the oil analogy works then -- it gets too expensive and alternatives are found. However, its just a matter of forking the codebase and starting another one...kind of like stellar did with ripple.

Many clones were made of bitcoin, but it has a large first mover advantage which keeps it on top. coinmarketcap.com has some interesting stats on the "altcoins"