This idea of FIRE has been spreading beyond techies/Internet nerds and into other highly paid professionals like doctors. [0]. The main difference is that non-programmer professionals generally don't get a thrill out of min/max-ing financial projections.
Such people might be willing to pay a few hundred dollars a year for someone to generate this kind of analysis with them and simply execute on it each year. Similar to how people pay for CPAs. My employer actually pays Goldman Sachs to provide a similar service for its employees (no commission, fiduciary advisors) but their tools suck compared to this.
[0] For example https://www.whitecoatinvestor.com/, https://www.physicianonfire.com/