On the 4th of December 2005, I moved from Sweden to the UK, starting work at ARM in Cambridge. At the time, I moved from an EU country to a EU country - albeit moving out of Schengen. With the Swedish passport being a "stronger" one (giving visa-free access to more countries) than the British one, there was no real benefit at that time for me to seek citizenship.
At the time, the residency gave me the right to vote in local elections, and with parliamentary elections being unaffected by me anyway given the rigged first past the post system, that in itself didn't seem like a reason either.
So I didn't bother.
But when I came up towards the 10-year anniversary, having moved in with my future wife, I did start thinking it might make sense anyway. I think at the time the residency requirement for acquiring British citizenship was four years.
But this is the point a bunch of spineless and/or opportunistic politicians, cheered on by the billionaire-owned media desperate to distract the British populace from how they were being plundered, decided that the problems with the country was foreigners existing. So a series of increases to fees, and adding of new hurdles followed. And the icing on the cake - brexit. I didn't really feel like falling for the negging, so put the idea away.
Then in 2023, we moved up to Scotland. .