The recent celebrity college admissions cheating scandal meted out its first criminal sentence this week — one day of jail for a former Stanford University sailing coach, already dismissed as time served — but at a larger level, it has revealed the insane lengths the rich and well-connected will go to when it comes to their child's chances of attending a top college or university.

Just how far and how wide do these tactics extend throughout the corridors of affluence in America? There is good and bad news from a new CNBC survey of America's millionaire population. Many wealthy Americans remain sane when it comes to helping their kids get into a good university or college, spending relatively small sums of money on the effort. But the signs of privilege in accessing elite educational opportunities are reflected in the results.

On average, American millionaires — those with at least $1 million of investable assets — spent less than $1,000 to increase their child's college entrance odds.

The most common effort made was not spending on SAT or ACT test prep and tutoring, but encouraging children (and grandchildren) to participate in athletics, arts or extracurricular activities.

Thirty-three percent of affluent parents recommend that their children get involved with extracurricular activities to increase their admissions chances, according to the new CNBC Millionaire Survey, conducted in May and which included 750 Americans representative of the affluent population. That was much more popular than paying for test prep and tutors.

While the dollar signs may seem small, research suggests that extracurricular activities represent a form of widespread social and income inequality. The New York Times' demographic and politics trends writer Thomas Edsall recently used the case of education as a way to evaluate the idea of meritocracy in America. He pointed to a 2018 article by Freddie deBoer, of the Office of Academic Assessment at Brooklyn College, that "holistic assessments" of college applicants, particularly of extracurricular activities and special skills and hobbies, are likely to favor the rich even more than test results:

"The student who is captain of the sailing team, president of the robotics club, and who spent a summer building houses in the Global South will likely look more 'holistically' valuable than a poorer student who has not had the resources to do similar activities. Who is more likely to be a star violin player or to have completed a summer internship at a fancy magazine: a poor student or an affluent one?"

The first person sentenced in the college-cheating scandal this week was the sailing coach at Stanford.