You have to conduct testing to show that the device is safe and effective before you can begin marketing it.

https://www.fda.gov/medical-devices/premarket-approval-pma/p...

If you've never gone through the process of bringing a medical device to market, well, I'm not sure there's an easy FAQ that will answer your scepticism. But the basic idea is that you have to do a bunch of testing in the lab, then probably a bunch in animals, then finally a bunch in human clinical trials, then you can actually market the device to the public.

Neuralink is in the 'animal testing' phase, and it sounds like they're likely to start human testing soon.

Note that once they've gotten a device approved for humans, that doesn't mean they will stop testing on animals. There will likely be improvements to the device, new protocols, etc. that will necessitate continued testing as new features are brought to market.

Nice link, thanks.

Relevant section:

> Among the types of evidence that may be required, when appropriate, to determine that there is reasonable assurance that a device is safe are investigations using laboratory animals, investigations involving human subjects, and nonclinical investigations including in vitro studies.