Yeah. Maybe it is just semantics.
To me, running hills while other kids are having fun hanging out is a sacrifice. Burning the midnight oil to study for an important test while others are going to a party is a sacrifice. Spending money on tennis instead of buying another car or taking a vacation to Europe is a sacrifice. Taking an adult course at a local college to boost a career while others are playing golf is a sacrifice.
Haven't done a scientific survey, of course, but I believe my thinking is in the clear minority on this. I think most families are not willing to make sacrifices to achieve success.............in junior tennis or any endeavor.........because as another poster said, this could lead to resentment.
Again, not trying to preach or convert. I am comfortable being in the minority on this.