Actually people did expect that, which is why the market does not accurately "price things in." People working in ML, Cuda, ~GPT2 were pretty confident in the eventual impact of AI and knew of Nvidia's monopoly on it.

There's a sort of midwit meme here where the naive take "oh this company is going to sell more next year, i should by stock at whatever price", -> "no, everything's already priced in" -> "if everything was priced in, you'd see a historic price graph as a straight line with a slope of interest rates"