In the end, it's not your company. You offered your sincere, thoughtful feedback, it was not taken seriously, and that is on them.
Had you "fought harder" you might have burned bridges for yourself and caused undue hardship and stress. They might have stayed the course regardless.
It's not your fault. It's not your company.
The best thing to do is to do the work to upkeep those relationships you felt were valuable. It's a small world, and a recommendation for your coworker's next position might be more valuable in the end.
In the end, it's not your company. You offered your sincere, thoughtful feedback, it was not taken seriously, and that is on them.
Had you "fought harder" you might have burned bridges for yourself and caused undue hardship and stress. They might have stayed the course regardless.
It's not your fault. It's not your company.
The best thing to do is to do the work to upkeep those relationships you felt were valuable. It's a small world, and a recommendation for your coworker's next position might be more valuable in the end.