To them it might be better than the ugly truth that the entire political machine of the US is blatantly picking and choosing who the leader is while throwing out the people's voice.

The reality is that the damage is already done. Since an admission that the election was rigged would cause more outrage among the masses, it's better to pretend it wasn't and dismiss anyone left saying it was as a "conspiracy theorist", keeping the idea that votes somehow matter alive to the general populace. There is little chance the Trump supporters will actually start the boog, so it's the best option.