The alternative has to seem better than the current situation. I've rationally brought myself to these places by feeling that the income and success is worth the price. When it stops becoming worth it, you change. That's why there's a prevailing wisdom that someone has to hit "rock bottom" before they change. In reality it's their bottom that they hit before they want to change and that bottom is different for everyone. It sounds like your bottom is at a higher threshold than your friends which is why there's a disconnect as you watch them do thing you can't imagine doing yourself.

I think the biggest way to help is to try to understand them and their values. Sometimes people are operating in a way that they don't even know is unhealthy. If you can simply get curious about their work habits in a positive way and then repeat that back to them without judgement: "It sounds like you value money." or "It sounds like you're scared of going broke in the future.", they can feel heard and it brings down their defenses.

But if you're saying "Stop working so much" or "You'll burn out." the person might be wondering why you're saying those things. Are they jealous? Are they wanting to hang out more? But if you can say "Hey, I've noticed you've put on some weight and I'm nervous about your health" or "Hey, I've been feeling lonely while you've been working so much", they might have a better understanding of your intentions which might help them lower their guard.