You are right in lots of stuff but you are probably underselling your skill combo. You are probably good (even if not great/amazing) at more than one thing - not just managing projects, but also sales, and maybe marketing too. You are probably right to say that there are other people better than you at any one of those things, but for the full combo, the story changes. It's easy to say "learn sales", and indeed it does not necessarily require very high IQ... but it may require that you change who you are. And that's extremely hard, if possible at all.