Well, on Ethereum, it's possible to do things that I never anticipated would be possible, despite programming nonstop for 20-whatever years: it is now possible to deploy a smart contract that does something useful and then lock yourself and everyone else out of it, forever. If there are no bugs, then it can be expected to do its job indefinitely without it being possible for anyone to change their mind and use their privileged access to change how the program works. This is called trustlessness, and it's the basis for a new kind of confidence.