All strategies have inherent risks

All strategies have inherent risks. A do-nothing strategy has perhaps the greatest degree of risk – the competition will move forward. A me-too strategy guarantees parity with the competition at best - but not if they execute better. And strategies, by their very nature, do not admit of experimentation and validation before-the-fact. They contain assessments, judgements, and decisions based on probabilities, not certainty. So, yes, they are guesswork.

In "The Halo Effect" Phil Rosenzweig identifies four areas of risk.
First – the Customers. Will they behave as anticipated?
Second – Business Competitors. What strategies are they about to pursue?

Third – the Company itself. How will the company respond internally to the strategy? Can it be executed profitably?
Fourth – Technological change. Never assume that the environment will not change. (Rosenzweig, 2009)
The first three above constitute the traditional C3 model of Company, Customer, Competition. Of these, only the first is moderately controllable; the others can only be guessed at probabilistically.