Sure there are many threats. That's why we have to keep progressing technologically so we can counter them (like the astroids etc). As mentioned before one of the biggest is humans themselves. We should all be obligated to do a 10 day vipassana retreat to figure out what really is important. I think that would make some real changes.
Let's state it simple: If you ask that question you are not ready to day trade. You need a proper plan and discipline to be able to daytrade profitably.