This seems more expected than surprising. At $3500 there is a very limited market willing to spend that and that market likely exhausted quickly. I wouldn't expect typical adoption curves for a product that expensive with limited value.
I think we're seeing similar adoption challenges with EVs currently. With current value props, a lot of consumers interested in current EVs have already purchased them and adoption rates are slowing. It's going to take a value leap (through better features and/or lower price) to jump start adoption again.
The same holds true for the Vision Pro, which I think most people knew -- it's too expensive and doesn't do enough. Assuming v2 does more for less money, it will jumpstart demand again.