I have seen another approach (also with STEM PhDs), where it isn't an income share, but rather that the incubator gets a referral fee if the student is hired--similar to a recruiter. Now, why do this? The math behind most of data science is rather basic for a number of PhD physicists--I would say the greatest weakness on the math front is that many will know probability, but not Bayesian statistics. However, the level of coding will be mixed with many not knowing about source control and a number coding in say Matlab rather than Python. Now, some have said that people can learn this on their own, which comes to the next reason. Physics graduate students and postdocs can put in extreme hours and their supervisors can expect those hours. 100+ hour weeks happen (especially for experimentalists--a number enter industry and it takes readjustment to figure out what to do with spare time). By formally leaving and joining an incubator, they give themselves space/time to learn--it's also a pretty intentional act where they have to decide that they are leaving the field (which can be psychologically difficult). The next is job interviews--the typical physicist has no idea what a data science interview will be like and coaching will help them a lot. Finally, there is networking, where the incubator may have connections with hiring managers where they can at least get people into interviews. I have seen people do either the incubator route or the DIY route and for those who have gone with the incubator (where they don't pay and the business model isn't a percentage of their salary coming from their pocket, but rather a recruiting fee going to the incubator from the company they get a job at), then they seem fairly satisfied with their experience.
