The secret to building Sustainable Business Models is to mostly ignore the "sustainable" part at first. The only thing that makes a business model last is its ability to create profit and genuine customer value. A business that can't stay in business can't sustain any kind of mission, no matter how noble. Too many founders get distracted by purpose-driven branding before they've actually built something that works. As Bojan Gajic pointed out on the Serious Sellers Podcast, you can't mortgage your future for short-term gains; true sustainability means thinking like your customer and delivering real value.
The nuance, of course, is that once you have a profitable foundation, a mission can become a massive differentiator. Thomas Smale noted on Honest Ecommerce that a business built just to chase a trend will die. A business built on a solid process is durable, and that process can absolutely include a social mission. It just can't be the only thing holding it up. Once you find a working business model, as Eliah Thanhauser said, you can add layers. Sarah Paiji Yoo did this with Blueland, showing you can build businesses that have a positive environmental impact, but that strength comes from a solid commercial strategy, not just good intentions.