And learning from the mistakes of others (part added by OP)....
Via article:
Tl;dr: they did way more squats than their normal routine. Their muscles released too much of a toxin (dead muscle fibers via rhabdomyolysis) and caused kidneys to not be able to get rid of all it needed to, causing kidney damage/failure. This doesn't always happen if a person is regularly engaged in intense exercise.
So when the article mentioned that they "Weren't used to exercising in general"
My first reaction was:
Talk about overestimating your capabilities. Good reason to point out that everyone has limits and in order to push those limits, one needs to work up to it.
So I decided to reflect:
There is much to be said about these kinds of things
"It's said that a wise person learns from his mistakes. A wiser one learns from others' mistakes. But the wisest person of all learns from others' successes." -John C. Maxwell.
While it is always advantageous to learn something from our mistakes, we have to discern when to learn from someone else's mistakes or another's success. Because someone with experience is said to have made a series of mistakes, learned from them and can therefore tell us the multiple things that we shouldn't do, based on what they are doing, successfully. We ask ourselves, or them, why they do something a certain way and not another, and are often met with the answer or discovery that it doesn't work that way, or it is less efficient. So, we trust those with experience over knowledge, because of this and the fact that experience is more often than not, knowledge applied, tested and proven.
This doesn't mean to always observe how another succeeds in a given task. There are times such as this article which illustrate the invaluable wisdom gained when we observe, note and apply what we learn from the mistakes of others. This also does not place any hierarchy on the three; both learning from our mistakes, other's mistakes and other's successes, as well as our own successes, can be equally invaluable. What is foolish is relying solely on one of these methods, and always ignoring the rest.
"The 1000-squat challenge is a fairly common challenge" but the lesson is to know that those who do it have some sort of regular exercise, and generally have healthy enough bodies to withstand and endure such. It is also noted that this instance is rare, but moreover just because there is a low likelihood, doesn't mean one should go about it unprepared, or unready.
In my early twenties, I had gained a significant amount of weight. Naively, I went right in to exercise apps with challenges, after being somewhat sedentary for a few years. I hadn't realized then, just how out of shape I was. Of course, I wasn't able to really complete them at first which was lucky for me, I might have sprained something or twisted another. I made a slow and steady approach after that.
Over the years, I learned just how important gradual improvement and intensity was. Not only is it great to start small when exercising, but in almost any other endeavor. Granted, there can be exceptions, but for the most part "one small step" can be a much more fortified and safe strategy, when gradually working up to "one giant leap" than just jumping directly in the deep end. We tend to expose ourselves to much more problems that way.
Everyone has their own strategy and there truly is not a right or wrong answer, just evidence based on the observation and experiences of oneself and others. Overall, if something becomes too challenging, and perseverance seems like it isn't enough, a change of perspective might help such as breaking one's goal into smaller and smaller steps to the right difficulty for them.