As founder of a startup, I know that at the start, you do whatever it takes to get initial traction, then find ways to replicate that via aggressive growth.
But almost immediately, you run into difficult ethical and practical issues. They aren't abstract like "don't be evil", it's far more practical: 1. Treat co-workers and employees with respect, and foster an environment of professionalism and empathy; 2. Don't raise customer prices or add fees without notice and consent; 3. Be precise in marketing, don't say "we do X comprehensively" when we really do 99% of X; 4. Don't over-inflate your security. Don't say "bank grade" security unless you know exactly what that means. 5. Don't offer services solely based on advertising. It suggests that you have the user's interests in mind, when you really have the advertiser's (this is a tough one, but necessary; even paying a portion of the cost would be a huge improvement). 6. Do not subvert the intent of your users. A photo sharing app should not analyze faces to build social graphs for another site. A VPN app should not analyze network usage for competitive intelligence. 7. Everyone spams, you shouldn't, but if you must, be obvious, and precise, and try to provide value in the email rather than just click-bait.
The list above is not terribly noteworthy, I know many small startups that adhere to it, but at least one big tech company that was in the news this week seems to have broken every single one. I used to think startups were scrappy little sketchy business-problem-solvers, and would happily cut corners. However If you're a multi-billion dollar company, it seems that you can cut corners without retribution.