In a relatively healthy economy, to a first approximation in the medium and long term, the amount of money you make approximates how much good you are doing. As a liberal, I'll be the first to say that this has a lot of flaws as a benchmark, but in general, if you cannot find people willing to pay for, or donate to support what you are doing without you having to live on ramen forever, there has to be some question about whether what you are doing is providing value to the world comparable to a standard job in tech, finance, sales or a professional discipline, as long as you are moderately careful about who you work for in the latter cases.