@silvers:
My only problem with this is that Intimidation is unique to King's Haki. This is why Hancock and Co. knew that Luffy has it in the first place.
I agree with Silvers, but I would like to tweak his statement and say that this intimidation ability you speak of is King's Haki. I will call it King's Ambition, or KA for short, to make it more distinct from haki.
In the most recent episode, 412, I haven't checked the manga, or it maybe it's in the manga as well, it was written or said of Luffy that: it doesn't matter if he has such huge haki if he can't control it.
So it must be either that KA requires a large amount of haki, or that a large amount of haki must be present in order to use KA. From the simple comparison given that it's 1 out of a large number of people it could be either. A different question we could ask would be, could a person raise the amount of haki they have or is it finite at birth?
On that question BB said something in Impeldown to Luffy saying something along the lines that Luffy's haki has improved. But in what way has it improved? In his ability to use it, or if it can be numerically measured, the amount.
With this set of information, I presume that haki is finite at birth, and that all a person could do is learn how to use it and make it better. I suppose an analogy would be you can train the strength of your arm through exercise, but you can never have any more than two.
If it's looked at in this way, it could be said that KA's is a trait unique to a person at birth, and the amount of haki is already present in order to use the ability. So it may not be useful to think of haki as something that could be measured but as types. But again from what's said earlier, it seems like there is an amount of haki, but this amount depending on the type is always large and small compared to the average. And the average is probably of all the people who have haki.
I think what happened perhaps is a misinterpretation of what was said, where if we say 1 out of a million people have a black ford mustang. Do we count in our analysis the people without mustangs? If yes then how is that useful to compare the rarity of a black mustang compared to other people with mustangs. And this is the one useful to us, since we are comparing KA's to other haki types. It might seem large, but if we say that mustangs are only sold in two colors, then we can derive that 1 out of every 2 people who own mustangs has a black mustang.
So for haki, we would need to know whether or not that statement included all the people in the world or simply the people with haki, that 1 in a million would be rare if it was limited to the set of people with haki, but would be misleading if it included people without.
I think what really happened was, that Oda meant the first, but the logically correct way to interpret the statement, if we had no other information other than the statement, is the latter.
Edit:
After thinking it over, I think there are no types of haki at all. That is, haki is it's own type. And what is being discussed is abilities of people with haki.