What are the best (existing or theoretical) uses of smart contracts?

Today I got rug pulled on a shitcoin casino nft-based ponzi get-rich-quick game.

It kind of shook my faith about what the platform is actually being used for, and I'm taking the opportunity to refresh myself on what is so great about eth.

Here are some of the ideas racing through my mind when I first learned about smart contracts, that I hope to one day see:

• decentralized uber
• decentralized airbnb
• gambling / sports betting where there is no house to take a cut
• decentralized check-splitting / venmo
• "use it or lose it" government stimulus payments

Here are some things I didn't expect that pleasantly surprised me:

• decentralized fiat/crypto on/off ramps
• organizing to buy the US Constitution

What are your favorite use cases for smart contracts? What are your favorite ambitions for the smart contract space that you hope to see ✨ someday ✨?