Good question! I think there are two approaches to it, one of which is interesting:
1. Why do sportspeople/influencers/singers make millions while young mathematicians/physicists/writers/poets/sculptors/etc languish in obscurity, most of the time penniless. Why did Yitang Zhang (https://en.wikipedia.org/wiki/Yitang_Zhang) have to do accounting of a Subway franchise and deliver food? Why did Abel have to die of tuberculosis and poverty. Posed this way, the question is mundane and the answer is simple: Most people value certain things and are willing to pay for them and are not interested in and are unwilling for other things.
2. However, there are stories that would be compelling to a mass audience. You mention Germain, her story would be a great period drama (backdrop of Revolution, being a woman scholar in an antagonistic society, etc.) There are many other similar stories: Maria Gaetana Agnesi, Sofya Kovalevskaya. This would be a great Netflix series, one episode for each perhaps. If these stories are not spicy enough for modern streaming tastes, e.g. not enough sex or adventure (Germain never married, Agnesi was very religious, Kovalevskaya was married), one can use biographies of Ada Lovelace (gambling, mad&bad Lord Byron, insanity) or Émilie du Châtelet (lovers with Voltaire, 'nuff said). Or, if there's production budget, Hypatia.
So the questions is: why are these stories not told more often? Hard to tell. Probably because (1) producers worry that any mention of math or science will turn off potential viewers (2) screenwriters ar just not that familiar with this people. I think (2) is teh larger factor.