People actually believe that there is an yet-undiscovered substance that has mass but interacts very weakly (or not at all) with light, and that there are vast quantities of this substance in the universe. They call this "dark matter".
The former will tend towards a defensive attachment to an idea which leads to, as Planck put it, "Science [advancing] one funeral at a time." The openness of the latter leads to less certainty, but greater ability for progress.
Consider the heliocentric/geocentric argument some centuries passed. Contrary to pop-science portrayals this wasn't an issue of Man against Church. The heliocentric view initially had numerous flaws and invalid assumptions. But because scientists of the time genuinely believed in the geocentric universe, they obsessed on these flaws and trying to use those to discredit the view, instead of impartially considering the idea and seeing if it could be patched and whether it would ultimately make more sense.
The "right" answer, with negligible refinement, can often look much worse than the wrong answer which has had decades, if not centuries of mass refinement. And that can drive those with a "belief" to the contrary, to want to attack it. The analogs outside of science are as endless as those within it.
