The Navy has an inordinate faith in defensive weapons such as lasers which have not been tested in true combat scenarios against technologically competent opponents. During the next five years the Navy will do all it can to convince Congress that those defensive weapons justify huge allocations for more surface combatants. The Army no doubt will be seeking big allocations for helicopters and armored vehicles. Wonder how many of the Congressional representatives would want their children to crew those ships, tanks or helicopters.
War has always been a very deadly business, with many unknowns.
The US Civil War, using somewhat basic technology killed more soldiers than many wars combined since.
If anything, Russia in Ukraine demonstrates that military doctrine, training and motivation are at least as important as technology.