Since there are several coins(tokens) on ETH block chain, it is not logical to accept those tokens for every contract use but rather use the fuel(gas) very small amount for every transaction.
And the contract never pays anything but the addresses moving tokens do.
Ah, thank you. That is the clearest answer I've gotten so far. I thought it was more like the contract creator had to put enough ether into the contract to keep it alive over its lifespan.
Now that I know it's not that I can start using my eth for some good. Thanks again.