Actually there's quite a body of evidence to suggest that when GDP is growing and income disparity is not significant, culture/sovereignty/immigration are not used as political footballs. When income disparity grows and GDP growth slows (or there's a recession), extremist politics -- usually centred around some sort of binary opposition -- rise. I.e. economics is everything, and people only kick up a fuss about other things when times are bad.

> Sovereignty

In purely semantic terms we are a sovereign nation irrespective of our EU membership. So it would be useful for you to unpack exactly what you mean by sovereignty. (IIRC the only way to violate one's sovereignty are: harbouring terrorists, invading a neighbouring country, violating the genocide convention, breaking nuclear non-proliferation.)

> Population density

Population density is fascinating to me because when you look at the 6m or so foreign-born workers in the UK, only 1.9m of them come from the EU. Bans on India, China, and Pakistan would be better ways to reduce population density. And, of course, if you removed all of the foreign born workers in the UK, you would see a massive reduction of… 24 people per km2.

I always thought people really cared about immigration's perceived drain on welfare. Which is why it's so funny that EEA migrants either a) overwhelmingly pay for themselves (pro-Remain numbers) or b) almost pay for themselves and certainly do a better job of it than the average UK national (pro-Leave numbers). Of the 7% of non-UK nationals who take up the welfare budget, Pakistanis are more likely to receive benefits than any other nation, and in the top 10 there's only three or four EEA nations.

> Culture

Left this one until last. The culture of Britain hasn't changed for the worse since Enoch Powell in the 1960s, Paki bashing in the 1970s, monkey chants from the football terraces in the 1980s, has it?