Do the Riddler's motivations make little sense?
He wants to get revenge on Bruce Wayne, so he has Two-Face help him steal enough money to build a corporation that sells holographic TV devices. It proves such a successful plan, he becomes rich and his company's stock outsells that of Wayne Enterprises.
He had won.
Then he went and did something stupid by trying to siphon the intelligence from Gotham City, which turned him insane and deformed. Then again, didn't he do that because he got addicted to knowing everything?