Isn't it possible to just go looking for another fast-growing small company when your current employer reaches that stage?
Of course you can go looking again. But why not look for a slow-growing or not-growing small company, so you don't need to go looking so often?
There are other issues with slow-growing or not-growing companies. When the company is not growing, people are incentivized to take a zero-sum approach to their work relationships. If the pie is not growing, you need to guard your own slice and take from others. This creates a toxic environment. If the company is growing, then collaborating on growing the pie can become the shared attitude.