Key points

The Sun influences the conditions near the Earth. The solar-wind disturbances disturb the protective geomagnetosphere. In turn, the disturbances of the geomagnetic field (a.k.a. geomagnetic storms) may affect the human infrastructures both on ground, in the air, and in space.
This has already happened many times in the past. The effects of solar activity do not cost lives, but they may cost a lot of money.
Solar activity predictions are an important aspects of solar physics. This is because of what was written above. People simply want to know the possible affection of their activities by spaceweather for the future. These people are not interested in the physical accuracy of the predictive models, only in their performance. That is why the experience-based predictions or modelling by mathematical functions (fitting) are very successful.