[shmeeed]

I think it's a mistake to assume that speaking the local language wouldn't be a good investment of time. It absolutely does change the way people see and treat you, even if you're not aware.

If natives choose to converse with you mostly in English, it's because it's (in many situations) obviously less friction for both - but to be recognised as having put in some effort changes your status (caveats notwithstanding).

Have you ever been on vacation where you could speak the native language (assuming you do speak any second language besides English)? It's a night and day difference, my friend.

If you restrict yourself to those areas of life where this effect isn't noticeable (e.g. an english speaking workplace and communities), that's okay, but you are effectively limiting your participation in the host society in a broader sense. I understand that can be a reasonable decision for any individual, but one should be under no illusions.