I'm going to have to disagree with you there. If you are planning on keeping the model y for 5-6 years, then purchasing it for $10k is WAY cheaper and makes more sense than the subscription.
When you go to sell, you are going to get some value out of the FSD purchase. Lets say 50%, perhaps more if you are able to sell private party, less if to a dealer, but lets say average 50%.
Right now....thats 50% of $12K, so $6k. Meaning, your real "cost" of FSD is going to be $4k. ($10k-$6k).
In 5-6 years? FSD is going to cost....who knows what. $15k, $18k, $20k? Honestly, the sky is the limit. At $20k....you are now getting $10k of resale value, so the FSD purchase was free.
Alternatively, if you did a subscription, at best case scenario where the monthly subscription stays at $200/month, thats $12k for 5 years. However, I guarantee you that as FSD continues to increase in price, the monthly price will also rise. People were surprised that when it jumped from $10k to $12k that the monthly price stayed the same. When it goes to 13k, or 14k? I bet it goes to at least $225, maybe $250/month. I bet over a 5 year period, you are easily going to be paying $14k-$15k in subscription fees.
Anyway, your real break even period of FSD where you are getting it for $10k vs subscription is 20 months. Like I said before, if NO prices change, your real cost is $4k, so at $200/month, that is 4000/200 = 20 months. If the FSD price or subscription price increases in those 20 months, then the break even point gets even shorter.
Now, the risks with the FSD purchase. If you crash your car, or sell your car earlier than the 20 months, then the subscription would have been cheaper. Or, if you would have been the type of user to only pay for a subscription to FSD when you thought you needed it, so you are continually canceling/resubscribing so you are not paying for it continually, then my calculations are not valid. But, I think it would be a very rare person that frequently cancels/resubscribes. Its more a risk where...with the subscription you get to "try it out", and maybe you decide its not worth it, so you are only paying for 1-2 months and then canceling. THAT is now way cheaper than the $10k FSD purchase.
My actual opinion of FSD, is that its awesome............ONLY if you are in the beta. If you are not in the beta, then...its only a slight upgrade from normal autopilot. But, you should really think that its not a $10k purchase...its a $4k upgrade at worst because you do get resell value out of it.
I'm always blown away by the Beta FSD software, and anyone I let test drive it are blown away too. Yes, its like a teenager on a learners permit currently, but yes, it does keep getting better and more reliable, though slow, and its fun to see that progress. I use it 90% of my driving in town.
It sucks that they haven't added anyone into the beta since Christmas, but....that will change soon (probably). I'm guessing at some point they do it a completely open beta where they let anyone with FSD into it that wants it, and I'm guessing that is before the end of the year. Hopefully sooner.
As an example though.....I'm actually a monthly subscriber to FSD. Why? Because I know I'm switching cars often and I'm getting a truck (cybertruck, or rivian, or....? I have reservations for all of them) sometime next year, so getting it for my current Y didn't make sense.