I would also like to know more about this, it's never been an issue for me personally but I contracted with a quite a few other freelancers who said it was rare

I would also like to know more about this, it's never been an issue for me personally but I contracted with a quite a few other freelancers who said it was rarely an issue in practise. I think you can keep freelancers long-term but they have to be willing to pay into a pension fund themselves if more than X amount of their income comes from a single client.