the salary will change over time. The gap will probably grow over time (increasing by % of income). Example, if both people get a 3% raise every year.... Ug. It is also possible/probable that the first job is a better job — better growth opportunities.
The point was that paying tution at BYU MAY be worth the amount saved going to another institution (based on a basic salary out of school stat). As pointed out, it MAY not as well.