In order to understand, and to detect, personal high treason, it is necessary that the concept of relative importances be clear.
Any importance is relative, because assigning an importance is an evaluation, and the implicit precondition of both is a basis of comparison: evaluating the importance of something is deciding whether and how much that something is more or less important compared to something else.
If the whole universe contained only one thing, in the absence of basis of comparison it would not be possible to evaluate it.
That being clear, the concept of personal high treason can be explained with this example: the ship is leaking through a damage, and to fix that damage and thus avoid sinking help is needed, but someone, instead of helping to fix the damage, devote themselves to polishing handles.
The seriousness of that is dual:
If one who polishes handles is unaware of the situation, the seriousness is in the facts, because rescuing the ship depends on the help given, regardless of whatever other matter.
If one who polishes handles is aware of the situation, but pretends not to notice, if one hides behind polishing handles so as not to confront the situation, the damage, the being in danger of sinking, and the need for help, then the seriousness, in addition to being in the facts, is in the conscience.
As the individual, with his conscience and his will, is at the basis of all the rest, as the conscience and the will of the group are the sum of the individual ones, if everybody, or too many, hide behind polishing handles, the ship will sink.
Here's what the importance of personal high treason is, and here's why it comes before all the other ones.