1. I'm simply not that important. There are millions of other people who have given this data to 23 and me and the like, and I'm just some rando peon - nobody is going to be specifically searching for my DNA.
2. The "worst case scenarios", e.g. getting health insurance denied because you have some gene, still seem implausible to me. Granted, there is a ton of stuff I thought would be implausible 5-10 years ago that is now happening, but something like this feels like it would be pushed back against from all sides of the political spectrum, even in our highly polarized world.
3. I haven't murdered anyone, so I'm not worried about getting caught up in a DNA dragnet. Sure, there can be false positives, but to get on in life you pretty much have to ignore events with low statistical probability (or otherwise nobody would even get in a car on the road, and that has a much higher statistical probability of doing you harm).