Why do some people lose their accents, while others don't?

Many people I speak to in English tell me that I "don't sound German", but instead sound like someone born and raised in the UK. Whilst I usually take this as a compliment, I do sometimes wonder whether the desire to adapt in order to fit in better with one's new environment should actually be the ultimate aim, possibly at the cost of one's true identity? Are we willing to pay this price? Or should we choose to proudly try to retain our accent (in my case German with a good dose of American English thrown in!), when settling in a new country, to express our very own history and identity? Is this even something we have conscious control over?

How do you all feel about this?

This article I read recently sheds a bit more light on this dilemma: https://theconversation.com/why-some-people-lose-their-accents-but-others-dont-linguistic-expert-201986