It doesn't really matter how good or fast you are at developing, starting a company is a whole different ball game. The overhead of winning and retaining clients will very quickly ruin any 10x advantage you have.
Side note: Judging from the story points it looks like this is a 23x developer not 10x ;)
The fact that they haven’t realized story points are like the score in “who’s line is it anyway” is a major red flag that they probably are not a 10x developer. Such a person would surely have ascertained the reality of the situation. The truth is that this person probably is above average in some aspects, but has a gross deficit in understanding the more nuanced aspects of the software business.
Side note: Judging from the story points it looks like this is a 23x developer not 10x ;)