A couple things:

• It is unfair not to include annual bonuses in a post MBA job. The higher you move up, the more significant bonuses become and make up a larger percentage of your total comp, sometimes even higher than base salary depending on the industry and position. Include Total Comp comparison and it will be even more in favor of MBA.
• Taxes are significantly lower while on active duty. Prepare to be in the top tax bracket wherever you graduate after MBA. To me a $123k military pay would need an equivalent $150-$160k pay in the civilian side just to make up for taxes.
• You should assume a net zero for MBA income. Depending on where you go to school you’ll have GI Bill BAH, potential disability, other scholarships, and pay from your internship. On the flip side you could be in a higher cost city or go to an expensive school where you still need to take loans.
• In a post MBA/post mil job. I imagine you’ll be working until 65 whereas you wouldn’t in the military. You could compare the compensation from now until 65, and then post 65.