Yeah they tend to train as if they are trying to win a bodybuilding or powerlifting competition where there isn't much separation between first and second place when it comes to strength or size but there's a huge differential in terms of rewards (both monetary and non-monetary).
Most of them probably didn't have tendons that just randomly ruptured. Rather they knew they had some tendinopathy and associated pain was building over time. They probably planned to get through the competition and then rehab the injury but the injury had it's own timeline.
This is really just another way of saying that training for competition involves different risk/reward decisions than training for health. Also why has nobody posted a research study that says that water is wet?