Big science is making big announcements (for example, see here) about the Alpha Magnetic Spectrometer (AMS) device attached to the International Space Station.
Another type of signature for dark matter has been found instead of just gravity signatures. There is now good data that suggests dark matter particles collide with each other and that they produce "ordinary" collision decay particles. So even though dark matter does not interact with light, these decay particles do and that is what we are seeing in the AMS.
OK. So to continue to be skeptical of dark matter, then I must explain data involving another whole type of phenomena in addition to coming up with a better explanation of dark matter gravity observations.
Dark matter just became more likely to actually exist, I think. This makes the AMS device a great bit of science.
But do I think the $2 billion spent on the device was worth that kind of information? Off the top of my head, that's about $5 for every person in the USA.
Truthfully, I can't say. I think it doubtful that a consensus argument can be made that society as a whole (each person, on average) benefits from such an experiment to the tune of $2 billion ($5 each). How can the numbers possibly work out? How can we come to a consensus on a dollar amount to assign to the results of this experiment?
And that applies to any dollar amount. What if the next dark matter experiment will cost $20 billion, $200 billion, ...? Is there any way we can avoid being arbitrary, capricious and whimsical in our spending on science? To have an engineering discipline in our spending on science?
This may be a more difficult question than the one on dark matter.