Etherium is a better coin since it also has the smart contract feature. There is nothing that you can do with bitcoin but you cant with etherium. So why not all people sell their bitcoin and buy etherium.
I suggest to read up on the reasons why Satoshi designed Bitcoin to not be turing complete. It's interesting information, will teach you a little about security and help you understand why so many hacks happen with various software packages. The number one reason is security.
You may have also noticed that as a decentralized system that ETH is a complete failure in living up to the hype. It was pumped as the "world super computer" that could do everything from issue ICOs, DAPPS, useful for businesses, smart contracts for banks and lawyers. The reason it's not capable of doing all this is as a decentralized system it's 1000s of times slower than the processor in my cell phone. Just think how single ICOs have totally bogged down the entire network, then imagine what would happen if a single popular DAPP was ever created (there are no popular ones in existence currently) that was used by the world population 24/7. The ETH network would be incapable of handling two popular DAPPs. The fact is a decentralized network is not able to do everything; but, might be able to do one thing well like function as money. The scaling debate for all decentralized coins demonstrate that even doing one thing well is difficult. Ethereum the platform might be useful for private chains; but, when you buy ETH the public token you're not getting a piece of that.
Bitcoin is getting smart contracts on side chains. This means the turing complete chain is one step removed from the money chain. Keeping the money chain safe needs to be the first priority.