Looking at the statistics in our clinics, eye floaters can be serious. We find that around 1 in 400 clients attending with a new floater have a retinal break. If you have a retinal break then it is very likely that there will be vision loss without treatment. If the break is detected early and treatment arranged immediately significant vision loss can often be prevented with laser treatment. If the break is not detected early then more invasive treatment is needed to repair the retinal break.
How risky is 1:400, well there are 365 days in the year. If you crashed your car about once a year you might think that driving around is quite risky.
And floaters are also associated with anterior Uveitis, see this link.