Well i mean if your natural talents and interest are enough to get you to, say 5th place on some stage how likely are you really to just give up at that and not push to place higher, what if you got second and knew you'd have a chance again next year. I bet sacrifice could describe a lot of the consequences of attempting to place higher.
Also, isn't literally every sacrifice just an opportunity cost? That kinda what makes it a sacrifice. Sacrifice your first born and give up the extra productivity possible. Sacrifice a lucrative but over taxing job and lose out on the money. Sacrifice a meal for someone and you go hungry. Sacrifice is always about the opportunity cost of the thing you're sacrificing. If it doesn't hurt, if it doesn't cost you something, it's not a sacrifice.
e.g. if you overtrain or don’t wait long enough after an injury, you may permanently damage something forever. Speaking from personal experience and knowing a lot of people who have done the same. There’s also some documentaries about athletes doing it and losing it all. Go the extra mile but don’t look back and have regret about that one time.
And since "important" is relative to the person making the sacrifice, it's easy for a person to declare something a sacrifice when what they were giving up was not especially important to them, or on the other hand for someone to dismiss a "real sacrifice" that someone else has made as unimportant.
Not that this matters, really. But I think it's important not to use them synonymously. In the case of an opportunity cost, you are acknowledging that there were things given up. In the case of a sacrifice, you are saying there were things given up _and it hurt_.
denotation and connotation. They have the same literal meaning (denotation) but certainly not the same implication and tone (connotation). Choosing to eat a turkey sandwich vs roast beef is an opportunity cost. I'm forgoing the roast beef. But it isn't really a sacrifice. I could say that it, and it would be true in some sense (denotation) but it would be very hyperbolic of me.
What if top-tier "greats" viewed every 'sacrifice' as superficially as roast beef vs. turkey? Even the ones we decidedly do not, like having a kid, starting a family, etc. vs. what they want to do?
Also, isn't literally every sacrifice just an opportunity cost? That kinda what makes it a sacrifice. Sacrifice your first born and give up the extra productivity possible. Sacrifice a lucrative but over taxing job and lose out on the money. Sacrifice a meal for someone and you go hungry. Sacrifice is always about the opportunity cost of the thing you're sacrificing. If it doesn't hurt, if it doesn't cost you something, it's not a sacrifice.