Platform is always an investment.
If you can abstract your internal infrastructure so that teams can build on top of it, do it. Not every abstraction pays off, but when you spot the right one and execute it well, the returns are remarkable.
The tricky part is knowing which investments are worth it. Not every shared layer needs to exist. But when the use case is clear, when multiple teams are solving the same problem independently, that is your signal.
But building it is only half the job. If the platform is hard to onboard, hard to understand, or requires someone to walk you through it every time, it is not really a platform. It is just code sitting somewhere with one customer.
The best platforms are the ones people adopt without being asked. Good docs, clear APIs, a smooth first experience. That is what turns an internal tool into actual leverage.
Build the platform, always. The compounding effect is real.