In fairness to the European politicians, there is no indications that increased military spending will provide any benefit
The actual problems such as an un-integrated Islamic minority, sub replacement birth rates and block obsolescence of European industry in the face of Chinese competition are not subject to military solutions.
Indeed, increased military spending towards some arbitrarily set 2% of GNP seems irrational at best.
All of Europe would be better off if Russia and its resources were fully integrated into Europe, rather than having it pushed into a reluctant alliance with China.
Is this so hard to see?
NATO has been around since 1949, and threats have come and gone in that time so perhaps, given the fact that military capability takes years to generate, looking about at any given point and thinking 'she's all good, don't worry about the money right now' isn't the right perspective? During that time, it has done a pretty good job of keeping Europe free of conflict (Not the EU as some claim), in fact when you look back at the Balkans it was NATO who eventually had to step in once the amateurs had been given a go.
2% of GDP (not GNP) is not a bad deal for guaranteeing peace and economic stability, and makes sense; the UK spends circa US57b on defence, but you wouldn't expect the same expenditure from Luxembourg, so as a metric its pretty fair. And to frame the argument about how onerous spending 2% of GDP on defence is, in 2020 Oman spent 12% of GDP, Azerbaijan spent 5.4%, Morocco 5.3% on defence. Luxembourg? 0.57% - perhaps next time they are invaded we can send a quarter of a military response?