In this case it's pretty much a rounding error. Median net worth for college-educated people in the US is < 300K [0] (and it drops fast for all other cases), so it's not far off from the annual income. You could plug the actual educational attainment distribution [1] and get finer numbers, but it won't change much for the purposes of this comparison.

[0] https://www.marketwatch.com/story/whats-your-net-worth-and-h... [1] https://en.wikipedia.org/wiki/Educational_attainment_in_the_...