For someone (actor -um-) to belittle someone, something, as an object, a plan (patient -on) with the use of disparaging remarks or attitude (inst i-), as when one attempts to dissuade someone from a particular plan; e.g., pointing out the defects of an item one is considering buying.
Nan udumnah nan adangyan, ya pumihuldah nan nun'awotwot.
As for some rich people, they belittle poor people.