We train for performance
Your performance may not be my performance.
It means different things to different people
But training isn't that performance.
If it is, either your ego is out of control, or you need to reassess your reasons for training.
Training is about improving
Gradually getting stronger, more mobile, more enduring
It's about increasing your potential
If you are in a competition, injury becomes somewhat acceptable.
Getting injured in preparation for that event, getting hurt in training that is unacceptable.
Yes, shit happens. But good training takes this into consideration and aims to mitigate it.
After all, if you're training to improve performance. How does getting hurt in training align with that goal?