Here are the reason why Lord Voldemort is an idiot:
1. He has no hair. We all wonder why he came out to be like this, and we also wonder why there's no spell to just simply grow your hair back. Voldemort is a genius, but not when it comes to using his great power to fix his bald head.
2. He is always wearing the same dark robe. Any fashion sense, mate? It seems not. Such a dull and not fashionable fool he is!
3. Barely any nose. What happened? I think he might have held his wand backwards one time and blasted it off his face.
4. Why so pale? I think he's sick... someone got him some Robitussin!
5. He could have been way more clever with his Horcruxes. Maybe bury them deep under ground, into the Earth's core? Or under Hogwarts, where massive digging would have to be done.
6. He killed Harry, a baby. Pick on someone your on size busta!
7. He doesn't seem to be attracted to any woman. You would think someone as powerful as him to have at least one slave lover! This means he's still a virgin.
8. In a world so big, why couldn't he find another way to come back to life without the help of someone else? I'm pretty sure there was a dead body lying around he could have possessed! Maybe someone as big as Hagrid?
9. Why pick a snake as your pet? Snakes are not the most dangerous animals in the world, a possessed eagle would have been better actually. Eagles eat snakes.
10. Voldemort has many followers, but most of them are idiots. If you were a smart wizard, you would pick a team of geniuses to follow you around and come up with better ideas.
11. Why not kill Ron and Hermione? Obviously, Harry would have gone mad and start crying like a baby on the spot.
12. Heck, kill Neville too! It was his fault Nagini died, get a clue and realize more shit is coming your way.
13. Why start a battle at Hogwarts? Obviously there's more students than your followers, so you're greatly outnumbered. Plus, why can't you just take it outside like the big guys?
14. There's a limit to the number of Horcruxes that can be made? Please don't tell me Voldemort ran out of time and didn't make some more!
15. Why let such a simple spell like Expelliarmus ruin you in the end? There's tons of spells he could have used to prevent that, and then proceeded to killing Harry. At least you'd save trouble.
aaand there you go, Snape!