You can "have your cake and eat it too", as long as you're happy with a smaller portion of the cake.

I own some NVDA. I've sold a good portion of it, so I've "locked in the profit" on it. If it doubles again, I'll sell some more. If it crashes I won't be too disappointed -- I've locked in my profit, and now I own more reasonably priced NVDA shares.

Note that if you have index funds, you probably already own a surprising amount of NVDA.