Actually, a USMA cadet’s financial ROI is infinite, since s/he and his/her family pay no money and take no loans up front like at other colleges, and the service commitment is that of a job that the cadet wants to do anyway, and with a much lower risk of unemployment at graduation than any other college graduate is likely to face.
To some people, financial ROI may not necessarily mean prioritizing the highest pay possible. It may instead mean minimizing the downside risk of being unable to find a job, or not being able to find a job that pays enough for a frugal independent subsistence at least.