That's a small chance. But,, it can still happen..which kind of scares me.
If you're scared of this, then you sure as hell should stop using banks and credit cards.
Because the chance of someone guessing your credit card details, AND your online banking credentials (AND winning the Powerball twice in a row) is still much, MUCH larger than someone accidentally generating your bitcoin address.
The chance of an asteroid destroying earth or a nuclear war is way higher.
Or getting struck by a lightning...twice in a row.