Defense Secretary Donald Rumsfeld said in 2004: "You go to war with the army you have, not the army you might want or wish to have at a later time." (The troops who got blown up due to lack of armored vehicles might not have fully appreciated his brilliance.)
That quote is damning to his legacy, whatever it might have been: we went to a war we started, that was unnecessary, and which will taint every history of the Bush administration.
Troops enlist knowing they may die, not sure what your point is. There is no army that fights a prolonged conflict without loses, no equipment is perfect.
At the time there was a distinct shortage of armored vehicles in Iraq and Afghanistan. Many troops were dying in IED and RPG attacks, and they were forced to improvise additional armor in the field out of scrap metal. There are always risks in combat and casualties are inevitable, but in retrospect the Defense Department leadership could have done a lot more at the time to accelerate production and deployment of additional armored vehicles and kits.
