Some nuance, but the answer is that it depends if the Cancer-rising billionaire became a billionaire before or during your marriage.

So for example, if you married a Cancer billionaire out of college, and they started a company and became a billionaire during your marriage, then yes, you would be included. If they were already a billionaire when you got married, then no, you would not be included. So, for example, yes Pricilla Chan, no Miranda Kerr). Miranda Kerr had her own money—but Evan Spiegel was already a billionaire when they got married. The reason for this is that I assume that the marriage played some role in the milestone: whether that be through emotional/practical support, networking, your mutual initial financial investment in the venture as a couple, etc.

I had to balance a few considerations:

1: Billionaires are a small cohort to begin with. (This list consists of over 10% of all American billionaires alive today, so it's at least an appreciable reflection of today's billionaires.)

2.: This already-small cohort is further reduced by 80-90% due to the limited availability of reasonably reliable birth times.

3. A tiny portion of these, that is, <10%, were born into billions.

With every inclusion parameter, the data size shrank the already small group.

So the criteria were essentially

1. Not BORN a billionaire, but became one during their lives (which does not preclude them from being born wealthy; just not billionaires); and

2: They took some action, whatever that action may be, to become a billionaire.

3. They had to have crossed the milestone at some point in their lives; they did not have to currently be a billionaire now (i.e. Martha Stewart)

For example, one became a billionaire through winning the largest-ever Powerball lottery prize; another was a white-collar criminal who stole money and was eventually arrested, all his assets were surrendered. Still, he was at one point a billionaire. And in reality, a lot of people commit crimes; very few ever reach billions, so it's still a very rare milestone, even if short-lived. However, only a small handful, fewer than 5, are no longer billionaires.

I was agnostic about how they arrived there.

I figure, I'm ultimately measuring a specific outcomes, and becoming a billionaire at any point in your life, no matter how you arrive there, is exceptionally rare.