As for the PR: of course it's true, but it worth considering that most fields wouldn't even dream of trying to get these amounts of money, because no one would stop and listen to their arguments why they need billions of euros, no matte how good their PR would be.
In the end, I would argue that past applications really are a large reason particle physics can even consider to have a PR-fight for billions.
On the issue of deciding where to invest money for 'knowledge for the sake of knowledge', I would suggest let scientist decide, what they like to do most. And of course there is a level of saturation and a minimum level below which a branch of science can't operate anymore at all. This minimum amount is unfortunately in particle physics relatively high, as you want to have at least one high energy collider in the world. Der Amerikaner ist die Orchidee unter den MenschenVolker Pispers
