The financial illiteracy of the general public.
For those out there that have spent 100 hours plus researching #bitcoin: what is the biggest threat?
Discussion
I agree, bitcoin is not for everyone but I think the user experience tends to improve and it will get easier and easier. Umbrel is a great example of this, it's very easy to install and run a node. Although in the future many people will use bitcoin without knowing what it is or how it works.