GP is wrong, in populism people never get what they want because the populist leader uses fear to control them.

One result of this fear play is that these people don't take the right decisions and thus fail to make their personal finances a factor in what they vote for, leading to economic losses.

The paper does try to look into some outcomes besides GDP growth, including indices of inequality and democratic institutions. They don't see evidence of improvements there.

Obviously these are hard to resolve in statistics, and people are biased towards their preferred pictures (both ways).