It's more complex than that. The Quebec paper suggests that there may be an association between the introduction of low-cost, universal Pre-K education and poorer life outcomes in some groups later on. Even with the 'natural experiment' that happened in Quebec it's still hard to prove causality.
But the authors explicitly say that high quality Pre-K programmes targeted at relatively deprived groups are beneficial. The take-home might be 'state-run, large-scale Pre-K programmes might be good for you if your home life already sucks but might be worse than the best quality care you could receive at home' (and even then I think you'd have to qualify the finding by measuring the potential positive effects on maternal incomes). They also say that the effects probably don't translate to Europe.
And... they offer the suggestion that you could significantly improve Pre-K education by focusing on (and measuring) 'non-cognitive' development. That seems like a good thing to try...
But the authors explicitly say that high quality Pre-K programmes targeted at relatively deprived groups are beneficial. The take-home might be 'state-run, large-scale Pre-K programmes might be good for you if your home life already sucks but might be worse than the best quality care you could receive at home' (and even then I think you'd have to qualify the finding by measuring the potential positive effects on maternal incomes). They also say that the effects probably don't translate to Europe.
And... they offer the suggestion that you could significantly improve Pre-K education by focusing on (and measuring) 'non-cognitive' development. That seems like a good thing to try...