Maybe Helium doesn't even have to clump together to act like dark matter. Maybe it just doesn't interact with light below the Lambda Point of 2.7 degrees Kelvin. This would change the relative abundance of chemical elements in the universe.

Visible matter in the universe is comprised of 3 parts Hydrogen, and 1 part Helium, and traces of other elements, for a total of approximately 4 parts visible matter.

source: https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements

"In the standard Lambda-CDM model of cosmology, the total mass–energy of the universe contains 5% ordinary matter and energy, 27% dark matter and 68% of a form of energy known as dark energy."

source: https://en.wikipedia.org/wiki/Dark_matter

So there is 27/5, or 5.4-times, more dark matter than ordinary matter. If all of it is Helium, it would be an additional 5.4 x 4 parts, or 21.6 parts Helium. This results in a revised relative abundance of elements, having a ratio of 15 parts Hydrogen to 113 parts Helium. This might break the Big Bang Theory of cosmology.

"Big Bang nucleosynthesis predicts a primordial abundance of about 25% helium-4 by mass, irrespective of the initial conditions of the universe.... The resort to the BBN theory of the helium-4 abundance is necessary as there is far more helium-4 in the universe than can be explained by stellar nucleosynthesis. In addition, it provides an important test for the Big Bang theory. If the observed helium abundance is significantly different from 25%, then this would pose a serious challenge to the theory."

source: https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis#Helium-4