2) Musk is particularly bad about it & does it in places that directly financially benefit him.
Telling people that if they fork out 15k now they'll have full self driving in X timeline, completely missing it and then doing the exact same thing for years on end seems less like the planning fallacy and more like fraud, but I guess we can just wait to see what the courts decide on the matter
He's not one though. He's a business executive, so someone who in theory who would have the job to reconcile those lofty dreams with reality.
However, I'd bet quite a bit that the actual engineers and software developers were that optimistic and certainly didn't believe they could achieve FSD in 6 months (they'd be horrible incompetent engineers if they actually believed that).