u/ErbilDustoff

I think this combo would take 26 -27 years, if you changed careers right after earning either of your master badges (assuming there is no way to earn time towards both badges at the same time).

Master EOD badge takes 8 years, plus a year or two of school

Master Aviator wings take 15 years plus a couple year school.

Is there some other combination of badges that would take longer to earn?