That you can't really help people without making money, having a profitable product/service/model.
Even the most selfless billionaires investor rarely want to burn a billion dollar in a money pit.
You can't work with people, who hate making money, who are so anti-capitalistic that the very thought of turning a profit goes against who they are as a person, no matter how benevolent or competent in other areas they are.
If you want to have any kind of real impact, you need to think like a business, a real business, except you'll just not be the one who benefits from the profits. You need stable revenue, profits, growth, even if it's to reinvest everything, but you can't be like "oh it's not about the money, we don't care about the money", the more of a non-profit you are the more you have to think about the money, unless Bill Gates is your daddy.
Of course you have to set to some limits in advance about the things that you'd never do, but you also have to be able to compromise, to see the bigger picture, if your decisions hurt 1 people to help 10 others maybe it's worth it, do no think in absolute, don't work with dogmatic people.
Also pay your people well, really well, a good salary spent on personal growth is an investment in the future of the project, just because money is not the ultimate goal, doesn't mean your partners/employees should have to deprive themselves. You can't perform if you can't take care of yourself.