Moral Competence
Competence and practicality are severally underrated among many people who believe they are doing good. This belief seems to often short circuit critical thinking and the person ends up diminishing their impact or having an adverse effect.Examples:
Habitat for humanity - for the cost of sending one incompetent american to build a house in the third world, an army of local builders can be hired. If you really want to make impact, donate rather than going in person.Talented and capable people who end up working low impact non profit jobs at low pay. If you had a real job and donated half your income to the cause, both you and the cause would be better off.Stupid advocacy. People who get excited about feel good slogans like "cancel rent" without considering impact on the medium and long term supply of housing, and thus end up amplifying the problem they believe they are fixing.These are just a few examples where not doing the seemingly good/moral thing can be much better than doing it.