Like if you are listening to those people, they are telling you with a straight face that unless you have a net migration of ~0.3%/year of unskilled African and Middle Eastern immigrants with a prime age employment rate of 60% (political incentives will make it impossible for you to go beyond that on a sustained basis anyway), in return for which you will have massive populist movements that make your country ungovernable and seriously degrade the quality of policy by creating a political race to the bottom even when they're not in power (which amusingly the same people implicitly acknowledge by sharing papers that find negative effects of populist movements on growth that dwarf any positive effects that can reasonably be expected from such immigration flows), you will somehow have massive inflation, much lower growth and your pension system will collapse 🙃 The good news though is that, as a consolation prize, you will also get a significant degradation of quality of life through increased crime and other forms of antisocial behavior in large parts of your country. If you oppose that, of course, you are a racist ignoramus who doesn't understand economics.