The death of the internet maybe? Though the chances are highly unlikely so that may just be a stupid opinion I dropped.
In my opinion, the biggest threat to Bitcoin is hackers and also permission from the government. These hackers can take the Bitcoin that we have. while the government has full control over what happens to the economic turnover of the country. And this also stings Bitcoin as an investment asset.
Uhm, no they can't, if you fully use how Bitcoin is supposed to work that is. And as for the government, no they don't have full control over the economy. I'd like to think of it as a partial control, but full control? Nope. Cause if so, then the progress would have been mostly positive all the time, and no recessions or what not could've happened. They at most could take advantage of disasters in the market to profit, but that's about it.
They can do it, if you are underestimating the capabilities of your cy then you are dead wrong, they have the ability to ban websites and services that are connected or even acquainted to bitcoin if they want. There might be some that will slip through the cracks but the witch hunt will be unforgiving if they want to and financial institutions will be in support of the government effort to eradicate traces of cryptocurrency because it is a threat to them ever since.
The chances of that happening are as close as what I thought of a threat is the death of the internet. Really, it isn't impossible, I agree, but what are the chances of it happening right? I'm pretty sure you're supposed to think of threat levels together with the chances of it happening.