Why did NASA give so much attention to the exiistence of Nibiru?

My best answer is that there are not enough amateur astronomers to watch the skys outside of Our own Nasa and Observatories in general being that space is such a vast place to begin with. It would take many eyes to spot something actually coming at the earth that would impact it. They may have thought about it and investigate the truthfulness that something may be actually out there. Afterall, Jupiter is tremendous in size yet we dont think its going to collide with us being in orbit around the sun and all like us. Indiscriminate objects...may just appear from nowhere. Almost like a far off car in the desert.