Be a company that promotes from within. Lots of people on HN will vehemently claim that promoting from within is an anti-pattern. But if you don't promote from within, you turn into the kind of place where the more an employee strengthens a skillset, the more undervalued they feel. That kind of resentment leads to an environment that either stunts employees or makes them act contrary to company interests. Both of those are dysfunctional outcomes.