Because no one has shown profitability, only made claims that are unproven so far. This combined with being one of the largest investments of capital since the rail system, and being backed by known conmen like Musk, make a subset of the population(myself included) sceptical.

If you are blind to or don't care about those caveats then AI looks amazing because it can legitimately produce novel results. Its just that for the subset that I am part of, it looks like they are doing so by burning a dollar to make 50 cents in revenue and that is not sustainable.