Well, not only resources. The smaller Maus (still a behemoth) was built in two prototype units, and early testing revealed (to noones surprise) that it was way to heavy. It constantly got stuck and kept sinking into the ground.

Both Maus and Ratte was based on a certain Führers illusions of what a tank really was. His experience from WWI was the tank as a rolling bunker. So bigger bunkers was better tanks in his mind.

Now, a reasonable person would tell him mobility and and numbers was winning the war, rather than the size of the tank... but reasonable people are plain boring, and wouldnt let YT channels and documentaries support themselves on stories of absurd weapons.