You don't have to act dumb (and you shouldn't). You just have to not act like a "rock star". The most brilliant devs I've ever met were people nobody would call "rock stars". They were collaborative team players.
That sparks my interest. Could you elaborate on what constitutes a brilliant developer from your perspective?
The other person will say “I will do these 5 things by next Friday.” And then next Friday all 5 are done. And they repeat this week after week after week.
Give me the second person every time.
This is why defining terms is important. For me, a rockstar is a developer who is just further along, who likes to program in their own time, who reads Hacker News, and builds projects on the weekends. Within 5 years, that person will be much further ahead than the rest and will spot pitfalls, security, and performance issues simply because they have encountered them before. However, sharing that information could lead to that person being called a "rockstar" and problematic, hampering "progress".
A more enlightening question is "what is a rock star" in my mind. A rock star is a dev who truly believes that they are the smartest person in the room, who looks down their nose at any work they didn't produce, who is only really interested in things that they think make themselves look better rather than things that will actually help produce the best end product possible, who insists on using the whatever latest shiny thing is in fashion over less shiny but more appropriate approaches, and so forth.