Inventarisation of biodiversity isn't 'knowledge for the sake of knowledge'.
If it would be done once, then yes, but done every ten or twenty years it would provide a lot of data to judge how important specific measurements of protection are. At the moment we are driving on a straight road in the night without light and don't know when there will be a curve, although it is very likely that there is one.

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 Menschen
Volker Pispers