&gt; selling my time to an advertising company than (say) running a programming&#x2F;compsci dojo for middle school kids<p>There are lucrative teaching jobs, and lucrative consumer products bought by low-income communities. But in this case, teaching dojos don&#x27;t scale the same way ads do.<p>Also, high-income communities can often incubate products that eventually become available to low-income communities, after they get over initial cost burdens.<p>Advertising <i>is</i> a good example though: If everyone uses ads, there is no individual (company) advantage to using ads, but you still have to use them to compete.