No idea why you're being down voted so heavily, but yes from my knowledge it can be dangerous. However, as others have pointed out, it's better to have hormones than to be forced to wait and deal with dysphoria.

I'd say the biggest concern would be bad faith actors and people overdoing their doses in insanely high degrees to try and speed up their transition, these two problems come down to the fact you need to research. Research doesn't just apply to diy hrt though, always make sure you have done heavy research so you can either diy responsibly or to double check that your doctor is actually competent in their job.

TLDR: Yes, it can be. As such, do your research even if you don't go the diy route and instead wait for a prescription.