it's the opposite. no doctor or insurance is going to change their policy based on a single result, you wait until a few separate groups have replicated the results. In the scientific community there is a reward (being cited) for pointing out that someone else's finding was wrong. The more important the initial finding, the more citations (and attention) you will get if you're the first one to correct the record. There's also a reward for building on an initial finding and going further, but you can only do that if the original finding stands. So one way or another the truth will come out.

Publishing a pre-print is only valuable if your result hold long term. You're just stating that you did it first.