I mean I used an example in another thread but take this.

Imagine there is a new disease starts affecting people. We don’t know if it is physical or mental.

The two biggest funders in medicine are government and insurance companies, both of them would benefit from this illness being mental, because due to laws and regulations they have to spend less money on mental illness patients. So we have a mountain of research funded trying to portray the disease as psychological. And no research attempting to find biological causes.

This legitimately happened to an illness called ME, only 40 years later through patient crowdfunding and tens of thousands of deaths later was enough research funded to disprove that it is psychological and show it is neuroimmune.