Find a local nonprofit or other organization you like and ask them what tech help they need. Many small nonprofits are starving for IT resources, either for financial or cultural reasons.
It's not glamorous, but if you're willing to volunteer your time helping with an org's Wordpress site or making sure everyone is educated about phishing and 2FA, you can make a meaningful impact in your community.
What are you doing to market your courses? Given Udemy's generous split when you drive outside traffic to your courses, it seems like that's super important to make money on the platform.
From http://americangut.org/our-results-so-far/ - "The American Gut project has many more samples representing more groups of people than other studies, such as the Human Microbiome Project, Global Gut, or Personal Genome Project."
No hard numbers on their site, but there's over 7500 contributors on their sample collection kit fundraising page.
It's not glamorous, but if you're willing to volunteer your time helping with an org's Wordpress site or making sure everyone is educated about phishing and 2FA, you can make a meaningful impact in your community.