Because they bought a Tesla with only cameras on it.

Admitting this would be admitting their Tesla will never be self driving.

Do Tesla fans think that? I've seen plenty of Tesla fans say that lidar is unnecessary (which I tend to agree with), but never that lidar is actively detrimental as Musk says there.

I mean, humans have only their eyes. And most of them intentionally distract themselves while driving by listening to music, podcasts, playing with their phones, or eating.