One problem with trying to work for the long term good is that it’s hard to steer due to lack of feedback from acting on the world. What lies at the Pareto frontier where you can actually get feedback but are helping the long term? Influencing policy might be an example as you can see whether there are short term consequences to what you’re doing. Any others?
It's a broad question, but I think feedback that isn't tied to 'real world' events is out of scope. I'm thinking of how for example a startup might make a product, put it in front of users, and then find out some need they hadn't thought of in advance.