Sure, low maintenance budgets are a factor. Longer hours (lower numbers of pilots), lower training budgets (same amount of knowledge is expected, but number of flights, number of weeks in pilot school (here, test pilot school), amount of practice hours are reduced.)
But look also at the ages of the machines: T38 was around in the mid-70’s.) T-38 A means this plane was in the first group of an early version of the original.
Sad. RIP.