Well, I think we know quite well how to secure websites. It's never perfect, of course, and not everybody is doing whatever they need to do in order to secure them, but there are ways.
Basically, we're talking about risk management here. Probably the cost to go from 99.5% to 100% is going to be too high, but you can get security that is pretty good. You just need to invest money and effort and be aware of what you're doing.