Competition, by its very nature, yields winners and non-winners. For individuals and teams (individuals acting collectively) the results of a competition can be positive, neutral or negative for them. For example, a parent who leaks information about rival children to college admissions officers might get a positive outcome (her child is admitted over the competition) and the competing children might get a negative outcome (they are not admitted). While assessing from the perspective of an individual or team is one way to approach assessing the consequences of competition, it is also worth assessing competitions in terms of their consequences for all involved. This is especially important when the competition is occurring within a society and is under the control of that society. The competition for educational opportunities in the United States is an excellent example of this.

When assessing the consequences of competitions for all involved, the results can be positive, neutral or negative. This is a spectrum rather than an absolute division and, of course, individual experiences can vary.
A positive competition yields positive value (which must be defined) for all those involved (which must also be defined). In an ideal positive competition, everyone engaged in the competition is better off by competing than they would be without the competition. This would include being better off than if the distribution of benefits was done equally without competition.
Friendly sports and games provide a paradigm example of positive competition. For example, while there will be but winner of a game of Risk, everyone playing it can have fun and thus gain from the competition. As another example, a 5K race will have winners and non-winners, but everyone can have an enjoyable run and be better for the competition. As a final example, some claim that an Adam Smith style economy can be a positive competition: while some business will succeed and others fail, we will all be winners because of better goods/services at lower costs.
A neutral competition has winners who gain from the competition and non-winners who gain nothing but suffer no harm from losing. While not everyone is better off from the competition, no one is worse off for competing. One example would be the sort of random drawing for prizes that occurs after races and other events. While some will win and others will not, not winning just means not getting a prize. It does not result in any harm.
A negative competition has winners who gain from the competition and non-winners who suffer harm or detrimental effect from their loss. In extreme cases, there might just be degrees of harm and winning only means being harmed less. For example, a liability lawsuit can be a negative competition in which the winner gains and the loser suffers a detrimental effect—such as being forced to pay a settlement.
In many cases a society can control whether the competition between its citizens will be positive, neutral or negative. It should never be forgotten that the nature of such competitions is a matter of decision. Deciding how these competitions will operate is a matter of values (ethical, economic, political, etc.). For example, a society can decide to make the competition for educational resources a positive competition: everyone gains, some are better off, but no one is harmed. A society could also make it a negative competition: the winners do very well indeed, the losers end up at terrible disadvantage and suffer because of it. This segues nicely into the overall theme of opportunity hoarding.
While a society will always have only a finite number of opportunities for children and there will be competition for them, the nature of these competitions can obviously be shaped by the collective choices of that society. This includes deciding whether each competition will be positive, neutral or negative. In general, making competitions positive will cost more resources, while neutral and negative competitions will incur less resource cost. To illustrate, making the competition for educational opportunities more positive would cost more than leaving it negative. As a specific example, the current model for K-12 public education is a negative competition: parents who can afford to live in wealthy neighborhoods give their children the advantage of better schools, while the children of the less wealthy often end up in poorly funded schools that hurt their opportunities in life. They often end up locked into poverty and all the harms that entails. Shifting this to a positive competition in which every child gets at least an adequate education would require expending more resources on the poorer schools, thus incurring greater cost. This would also entail that the better off would have less advantage over the poor in terms of education—they would still retain the advantage of better schools, but the gap would be smaller and thus the competition they face in other aspects of life could increase. This is one obvious reason for opportunity hoarding: the less capable the competition, the easier is victory.
This example could, of course, be challenged. One could argue that the education system in the United States is already a positive competition: even the poorest Americans are supposed to get free K-12 education and even the worst public education is better than nothing. While this does have some appeal, the same sort of reasoning would seem to lead to obviously absurd consequences. For example, imagine the competition between a person intent on date rape and their intended victim. It could be argued that the competition is positive: the victim could get a free dinner and drinks, although they are raped. While they did get some “benefit”, the harm is far greater—they would have been vastly better off without that “competition.” I do not deny there can be grounds for dispute over whether to cast a competition as positive or negative—there obviously can be. There is clearly a challenge in sorting out the classifications and there is also the matter of degree to consider.
As such, if someone wants to characterize the current education system as a positive competition, they can do so—as noted above, the students in the worst school in America do get more than nothing. In this case, one would need to recast the discussion in terms of degrees of positiveness in the competition—how the winners and losers fare relative to each other.
While each competition for opportunity would need to be assessed morally, I would suggest a general guiding principle. When our society is shaping the competition between our children for opportunities, the morally right thing to do is to make them at least neutral and there should be every effort to make them positive. After all, members of a society should strive to avoid harming each other and this is especially true when it comes to the children. We are, one would hope, friends and not enemies.