For what it's worth, this is how it works for founders too. The amount you pay is stupidly small (usually well under $100), since the strike price is essentially $0. There's no legal designation for founder when it comes to stock, so this person just got the same deal the founders did.

This is actually a great deal when the exercise price is low enough. You pay a nominal-ish amount up front to exercise early and all gains are LTCG. It is not a good deal in any situation where you’re not getting in close to the ground floor though, if the exercise cost itself is substantial.