A great engineer is not expected to know how their impact on a 25 person company will be different than a 200 person company. Moreover a great engineer may not yet know that not having that impact may be a really important loss to them.

I'd still want to hire than engineer though. But when they decline, I'd rather them not tell me it's because the other offer was $10K higher. I'd rather they tell me they see more room for personal growth, more interesting technology, etc. There are reasons to decline, and that's okay -- but $10K is a really stupid one.