1. The weather forecast. Do you think those dark and stormy nights for plotting just show up?
2. That your HR department has been able to replace all the minions slain in your last evil plan.
3. That you don’t clash with anyone else’s. There’s nothing more embarrassing than attempting a minor coup only to find that Dark Lord Nasty is going for world domination on the same weekend.
4. That enough heroes know about it to make it interesting. Have you pinned enough notes to the walls of inns with daggers?
5. That your one weakness is cunningly defended by an elaborate dungeon full of traps and things (and possibly Things). It won’t make any difference, but at least you can tell the insurers that you tried.