History always repeats itself
The history of the IT industry is littered with cases of successful small European companies who sold out to large American ones, and then many of the best people left. If you'd held a senior position (managerial or technical) in a business you'd helped to grow from almost nothing, would you want to become a small fish in a very big pond?
Maybe there should be better ways to reward people like this, without them having to sell their shareholding to anybody they can find with a large enough wallet, and walk away from what they've achieved.