Any examples of profitable smart contract ventures from solo founders?

There many ventures (eg. https://nomadlist.com/, https://retool.com/) that were launched by solo founders and were made profitable.

Are there similar example from the crypto world. I wrote Smart Contract because Solidity is a tangible thing I understand (and I expect a solo developer to be able to designing and deploying a smart contract on Ethereum) but also interested in solo founders launching consensus based systems and be able to sustain themselves from the project.