Friends who give ultimatums like this are usually toxic and worth ditching. Your friend would be better off cutting you off now, regardless of what they decide about the job, than continuing to associate with someone who'd emotionally manipulate them over a career choice. Healthy relationships simply don't look like this, and dressing it up as principle doesn't change what it actually is.

The fact that this feels like a normal thing to say to a friend tells on you a bit. Get out more, spend time with people who don't already share your priors, and the certainty starts to sand down on its own. Threatening your friendships over someone else's career is not the moral high ground, it's just an ugly way to treat people. Humility is understanding you can be wrong about things even when you're certain you're correct.