What Are Some Things Every New App Founder Should Know? I Will Not Promote

I’m working on a new social platform and have only one solid year of “startup experience”. When I first began, I didn’t even know what a C-Corporation was. Now, after gaining a few reliable income streams, I’m bootstrapping all of this and I’m in the stages of creating a timeline, vetting a developer, deciding a backend solution, and creating UI designs and wireframes. A few things I’ve learned about along the way:

• Corporate business structure
• Funding, grass root investments
• Finding co-founders
• Startup accelerators and incubators
• Pitch decks and explanations
• How to use Figma
• Teamwork and collaboration
• Mentors and connections
• Demographic research
• Market validation
• Pivoting
• Financial structure
• International laws
• Programming languages
• Feedback on new ideas/flow
• Security and penetration testing
• QA and Beta testing
• Constant reiterations and changes

What are some other problems/knowledge you or other founders have discovered along the way?