Now that being said, when it was launched, 23andme was the only way to have very affordable and high-quality and reliable DNA scans.
This data is very useful to improve your quality of life today using tools like Promethease. This to be weighted, against a risk that "potentially" someone may use maliciously in X or XX years.
There is also the "risk" that they use this data to develop popular medicines that will actually help your long-term quality of life (if you can afford it).
It is a very valuable service if you’re Jewish, that others like Heritage.com don’t. Where can you get it otherwise?
I think people knew this would happen, eventually. The real question is whether they cared. To most people, protection and privacy of data like this is still an abstract concern. I suspect that won't change until a serious data leak happens or something along those lines - although I hope I'm wrong.
If these companies were required to put up a big banner before you check out saying "By purchasing this and giving us your data we have the right to sell it to whoever we want" with examples of how the data may be misused by bad actors people may think twice. Not everyone will, but I suspect it would be more effective than you think
Why would someone care whether or not it would be sold if they didn't care enough to provide their DNA to an unknown company to begin with?
You're making an argument about a concern that doesn't even exist in the average person's head.