Why does standard model lose predictivity if it has unstable vacuum? In String Theory In A Nutshell by Elias Kiritsis, 

Standard Model is unstable as we increase the energy (hierarchy problem of mass scales) and the theory loses predictivity as one starts moving far from current accelerator energies and closer to the Planck scale.

How is predictivity related to instability of higgs vacuum? Is this about QFT predictions done perturbatively, such that we cannot describe particles in middle of transition? Or something else?
In any case my question was confusing: it is just asking why we have predictivity problems when we have an unstable model.
 A: When you have an unstable equilibrium  , even in classical mechanics, these predictions can be random. Which way will this rock fall in a small earthquake?

The angle cannot be predicted, because it depends on many factors, from the direction of the quake to the localized  strength of frictional forces holding the rock in the unstable equilibrium.

it is just asking why we have predictivity problems when we have an unstable model.

In the classical case, it is too many variables needed for a safe prediction.
Quantum mechanics is inherently probabilistic, and this means that factors influencing stability will enter with a probability . In the simple case of crossing an energy threshold, as with the Higgs mechanism, there are quantum mechanical probabilities of how this threshold is crossed, which , by construction of quantum mechanics can only predict probability distributions. In the case of a universe, as we live in one universe we just get one throw of the dice, and calculations may   not give  predictable angular or mass or energy distributions, quantum mechanically. 
