A lot of us who volunteered back then, were (at least partially) motivated by the draft.
Draftees did not get choices that volunteers did, as fast as Service entered, service shools, various alternative time-plans (i.e. 2-2-2-2: Res-Active-Res-Inactive Res etc.) or trade offs of total time Active in exchange for immediate service, etc.
Draftees got Hobson's choice, and Hobson was a notoriously capricious Assignments Clerk in the Practical Joke Department.
IOW, there were distinct advantages to volunteering, as opposed to being drafted; and drafting was fairly likely.
"A lot of us who volunteered back then, were (at least partially) motivated by the draft."
Kerry has admitted as much, it did steer many men into the navy and air force, but almost 80% of the combat deaths in Vietnam were volunteers, not draftees.
I myself fought a lottery number of 14 for two years, won a permanent deferment and then enlisted in the army.