Wind energy is currently responsible for about 15% of the energy produced in Europe. So relying on wind is absolutely impractical even if we invest 10x more tha

Wind energy is currently responsible for about 15% of the energy produced in Europe. So relying on wind is absolutely impractical even if we invest 10x more than we do, and you would have to prepare for days with low wind availability in the whole continent as well, because they do occur. The problem you describe is serious, but I would guess over 90% of nuclear power generation in the continent remains unaffected, if not more. So a grid here makes a lot of sense, and works as a reliable alternative. It is also pretty easy to design a grid that does not rely on the same types of reactors.