1- Prepare for the worst. Don't assume something won't happen that is possible. Preparing for the probable is usually hindsight.
2-Hope for the best.
3-Expect something in between with luck.
I realize you can't plan for every problem. A meteorite could hit a drilling rig, but I wouldn't plan for that. A massive wellhead failure is a very real danger. If they happen in other places, why not at such depths? Drilling in such deep water with no new and tested technology as far as I can tell is madness.
In addition, having no serious money put into research of new and more effective means to clean up an oil spill is criminal IMHO. Research into methods to operate at those depths effectively should have been developed.
It looks like R2D2 is down there trying to shut the thing down.
Edit: I am the knower of all things. You must obey.:sarcasm: