Curious about whether or not saving your GI Bill for a master’s or doctorate-level degree has any benefits?

My wife just separated from active duty, we are anticipating her acceptance to a BSN program starting in the Fall of 2025, and seeking information on whether or not to save her GI Bill in the chance she would want to pursue a higher-level degree. As it stands, she should be eligible to receive the federal and state grant (Cali resident going to a state university) while enrolled in the program which would cover the cost of tuition at her school.

I don't anticipate her wanting/being able to pursue her higher level degree until around 4 years after she obtains the BSN, my thought is we would miss out on investment return from the 4k monthly she would get from MHA if using the GI Bill.