A rational goal would be to balance "risk and reward" and close down higher risk activities that are not severe penalties so as to keep hospitals up and running.
However, the problem is that each of us has different risks and different rewards.
As it relates to this particular question, for each individual player the "reward" is that they've put in tons of work to get where they are, some of them are trying to showcase their skills for the next level, and others just love the game and don't want the choice to play it taken from them. For those players, the "risk" is largely something they can EASILY put out of their mind, because they say "most people my age don't have ill effects from this virus."
For a University Board of Directors or an athletic conference as a whole, the "reward" is money, fan engagement, student engagement. The "risk" is getting pilloried in the media for making a wrong decision which leads to the death of one (or multiple) players, significant numbers of hospitalizations and/or long-term health problems, etc. Not to mention when that media criticism dovetails with already too many discussions about players being "exploited", the question of whether they should get paid when it's a multi-billion dollar industry, etc.
For us as fans, the reward is the enjoyment we get from following our team. The risk is absolutely minimal--as devoted fans and supporters of our alma mater, we obviously don't want our own alma mater to be singled out for doing bad things. But beyond that, players potentially getting sick has very little effect on our lives in any way.
In this case, the University BoD and the athletic conference big-wigs have the power to make a decision. The players don't. The fans don't. Neither group gets a vote. So, for better or worse, the university and conference officials' determination of the risk/reward balance is the controlling one.