If it's obvious to anyone with a telescope, that at least Jupiter is a sphere, why would Earth be flat?
One answer I hear from flat earthers is that other planets are round, but not Earth.
The other answer is that space is some sort of projection, and you're not seeing planets are all.
I don’t think it’s flat, I think that technology is not nearly as advanced or far-reaching as we’re told. Remember, all of these organizations are lead by snake oil salesmen.