How is running a startup better than being the CTO of a startup?
- Instead of leading an eng team, maybe CTO meant "our entire tech team".
- Maybe the founders sucked, or had personal conflicts.
- Maybe the business was broken in ways a technologist can't fix.
- Maybe the business was viable but this individual did not enjoy being a part of it. Could be anything from "there are too many salespeople yelling into phones all around me" to "the technical problems were not the sort I am interested in / good at solving".
Not all companies are like this, but smaller ones that are looking for CTOs (whether due to founder splits or turnover) often are.
The other thing that sometimes happens is when a CTO position is carved out for a company that is doing well but needs "maturity," typically due to missed deadlines/etc. This can be a pretty terrible experience unless this sort of thing floats your boat - a lot of the downsides of working for a large company, but still the risks of working for a small one.
The two co-founders had personal conflicts; the business was broken, and never became viable. And a few other things...