Thanks, yea I've realized that there is little incentive to share this out, upvote, etc. I think Smart Contracts are a great way to test out some of these game theory scenarios though :)
IMO, ERROR: PLEASE INSTALL METAMASK TO USE THE BUTTON makes the contract meaningless.
Yeah, this seems like a ploy to get people to install some shady browser extension.
Good point, I'll change the message. MetaMask is a common browser extension which allows you to interact with Smart Contracts on the web. Other alternatives are Mist, Parity, or myetherwallet.com
There's some incentive, since the pot goes up every time someone clicks the button.