What I'd tell myself about startups if I could go back 5 years
> A good developer can pick up any language or platform in a few weeksYes and no. There's a major difference between "picking up" and actually being good at something. If you have nobody on the team that is either already intimately familiar with the language/platform, or has experience with various languages/platforms, you're going to be spending a lot of time figuring out how to do stuff properly instead of just building stuff. And if you are a startup with a limited runway, that difference is crucial.