In the run up to WW2, the US government made a very big deal of socially incentivizing military enlistment. The GI Bill offered education and housing benefits. Military work was competitive with the private sector and you had lots of off-ramps into the civilian side of the government. Military families enjoyed local prestige, particularly in the officer’s corps, so it was a good stepping stone up the socio-economic ladder. And the military operated as a strong network for business advancement, both as a military contractor and as a civilian with a tight-knit social circle of ex-military friends and neighbors.
All of that has been dissolving since the Vietnam Era. Soldiering isn’t considered a particularly noble profession. The pay is shit. The benefits have been cut back enormously. Enlisted pay is worse than service sector work and military families often live in poverty. There’s no real path to career advancement and enormous liabilities that come with 5+ years working around dangerous military equipment.
40 years ago, you could make a litany of arguments for why military service was personally advantageous. Today? The only reason to join is because you’ve got a shot at some brass, and even then you’d be way better off angling for a high paying civilian role.