To paraphrase Mark Steyn, the real problem with Socialism isn’t just that eventually you run out of other people’s money, it’s that you run out of other people altogether.
The problem with using immigrants to prop up declining native populations is that you have to make sure the newcomers don’t murder more of the original population than they replace.
Europe apparently hasn’t figured this out yet.
The rule of thumb is, whenever you have a nation that has more than two (2) White people, you need the diversity.