I think the reason you, and many people do not choose the premium connectivity is because psychologically, most people dislike ongoing monthly payments. I just gave in and paid the extra to avoid amazon prime adverts, and it was stupid that I had not done so before...
I even bought FSD, here in the UK, where it is basically useless for now, because I prefer lump-sums to monthly payments.
Looking at the maths, Tesla should definitely sell lifetime premium connectivity for $1,000. I bet a lot of people would add it at purchase time, and unless everyone keeps their Tesla longer than 87 years (very unlikely), its still a win for Tesla. They could even sell it as '10 years of premium connectivity' to cap the risk.
Its all a rounding error compared to FSD, assuming it continues to improve, and to roll out to the rest of the world. I see a lot of hints that there is progress regarding FSD in China, and also in Europe, from various X accounts.