You are indeed renting a machine to run some code, and if you want many people to use your code you want to make it cheap. There's a trade off.
You can fuck up things on the BTC blockchain too, "burning" crypto by sending it to a dead address has been a thing for a long time.
It always seemed stupid to me that it was possible, compared to sending money to an invalid IBAN, but I'm not a crypto enthusiast so I may be biased.
Of course you can do both things, which is why catastrophic financial ruin is a daily fear when dealing with cryptocurrencies.
https://www.quora.com/How-can-I-find-my-Bitcoin-cash-that-I-...
Giving a person control over the funds allocated to their smart contract probably opens holes where they can steal the smart contract's money, though obviously creating software that handles money and can't be updated is its own kettle of fish.