The question isn't whether someone would work for $250m but would not work for $150m; the question is whether someone would or wouldn't work for you for that amount. If someone else offers $200m to the same person, they would work for you for $250m and wouldn't work for you for $150m.
Warren Buffets salery has been $100.000 for decades. And as far as I know Berkshire doesn't do stock based compensation at all, Buffet just holds the shares he always held.
To beat competitors, not have tons of beemers for beemer sake. The motivation is relative. The 3 big "robber barons" of the late 1800's use to send each other brag-grams over who was richer.
Surely it's just for keeping score