As I wrote earlier, 8s are prone to denial of vulnerability, but the 'weakness' of this type is that ultimately, there is some level to which you cannot achieve this without the (neighboring) attitude of E9, which involves a kind of numbing of the self (basically, an "I don't really care/I don't really exist anyway" attitude). That is, the more one is conscious
Denying vulnerability is not the same as actually being powerful enough to warrant the denial -- there are many 'dumb' versions of each type, and the dumber versions of 8 vastly underestimate what they have to lose. The bubble can burst on an 8, which is when they're actually proven to be powerless against their will, and that is when they disintegrate to 5.
A 6 CP does tend to 'deny' vulnerability but more in the sense of being on guard at all times or proving to themselves they can overcome danger. An 8 tends not to see such a need, but again, this says nothing as to who is actually RIGHT -- in the end, being powerful/not is independent of type.
Illustrated with Pokemon, Mew is far from an 8, but could destroy many who are probably 8s. It probably doesn't think about doing so all that often.