Your coach is a moron. Don't take his stupid advice.

Because you'll try to just "walk off" a serious muscle injury that needs rest and fuck your shit for life. Especially at that level with the amount of physical force those dudes produce.

Playing through small injuries leads to larger injuries. If your coach were paying you thousands or millions of dollars per game, they would not want you to wreck yourself and end up missing games.

Protecting their investment?

Well, has your coach ever trained any pro athletes, or do they always seem to be unable to make it there?

It's like when mommy and daddy buy their precious little Timmy a car and then he doesn't take care of it, doesn't keep it cleaned and maintained, and runs it into the ground. Timmy doesn't care, it cost him nothing, and mommy and daddy will get him another if that one breaks down.

Compared to:

Timmy worked his ass off to buy an expensive, high end pickup truck for the work he does. It took a lot of work and sacrifice to be able to afford it, and without it, he doesn't make money. So, he takes excellent care of it, keeps it clean and maintained, and he's careful about how and when he uses it.

Because those millions of dollars are an investment in a long, profitable career. "Take the day off and rest" versus "keep pushing and do irrecoverable harm to your body," which do you think is preferred?

Well one your coach is a moron.

But also they're worth millions and millions of dollars. Why would you risk an asset worth millions and millions of dollars because a coach is a moron?

Because they’re grown adults weighing 75-150kg depending on the sport and position, with strength and conditioning to match, and you don’t want to shatter your knee just so you can make a single play in a single game, but end your career (remember that bit about how much they’re paid, and how much the team paid for them?)

You don’t want a person on a contract with multimillion dollar injury payouts to get invited and have to also pay someone else to fill their role.

In high school you're younger, weaker and lighter. Also, the coach is trying to toughen you up. Not saying they're always wise about when to send you to the bench, but it's nothing like the pros.

Once you get into the pros, those guys are monsters, fighters with a lot more to lose. And of course they're literally financial investments.

It's precisely because teams are signing multi million dollar contracts with these athletes. These organizations are smart enough to know that they will get a better long term return on investment from these athletes if they get proper evaluation, care, and rest from an injury than if they push the athlete to "play through" the injury.

Professional athletes are also much more self aware of what is an injury that needs rest and what is something that they can play through. See for example George Springer immediately taking himself out of the game during the World Series, knowing that it wasn't something he could just "tough out".

i think you are posting about European football.

The players don’t get take off the field for something minor. They get taken off the field because of serious injury to multi million dollar assets or to waste game clock…

Most pro athletes are playing through minor injuries. Some play through major injuries. There is a bigger focus on concussions now that might result in players getting pulled out, in pro leagues now though.

For younger kids, it's highly unlikely they actually have a serious injury. Many complain about minor bumps and bruises. There should still be care for head injuries specifically, but it's pretty rare for kids to get a major injury that's not readily apparent.

It depends on the sport. There are sports where people absolutely play through injuries. Hell, the NFL only recently implemented a concussion protocol.