10% isn't all that expensive in the early stage, especially for a high growth software business where it will be diluted off very quickly in subsequent rounds. If we're talking hardware or research, where a significant amount of time and effort (and possibly money too) has been expended, then yeah, 10% won't make much sense (it still might, based on the exact space your product is in). I think YC themselves say that the best time to apply to it is just after the initial validation (which doesn't work for hardware or research).