Differences Between Stratagey and Tatics

Why is 'strategy' difficult to achieve, let alone sustain? When does it ascend from mere tactics? 
With some grateful borrowing and adaptation from Carl Von Clausewitz, I find six connected reasons. 

First, competence in strategy requires mastery of a challenging complexity.

Second, by its nature strategy is more demanding of the intellect and perhaps imagination than any structurally more simple activity—policy, operations, tactics, or logistics for prominent examples.

Third, it is extraordinarily difficult to train competent strategists, let alone outstanding ones.

Fourth, strategy is extraordinarily difficult to conduct with consistent excellence because of the unique physical and moral burdens it puts on would-be strategists.

Fifth, it is worth citing what Clausewitz termed friction, although the previous point can be seen as encompassing aspects of this phenomenon.

Finally, success in strategy calls for a quality of judgment that cannot be taught.