I am all against bubbles and irrational valuations etc. but I think in this case the prospect of future growth was fully justified. There are never guarantees, but Nvidia's price went up 10x or more in three years and e.g. their PER stayed mostly flat. But their PER of 50 three years ago would be 5 today, which would be extremely undervalued. I would say the "market" got it correctly this time.