Web was absolutely a fad the first time around, and that bubble famously burst in a most spectacular manner. AI has been a fad several times, so much so that the term "AI winter" was already coined decades ago. Mobile is a very successful tech, I give you that, but it too had its false starts, and people who thought they’d be the next Twitter in no time if they "just have an app" were dime a dozen a decade or so ago.