I'd like to add that most people don't understand the research, development and procurement process, nor how long that can take for major weapons systems.
Most focus on bullets, rifles, and tanks.
They don't think about a high tech fighter plane or drone that cost MILLIONS PER COPY.
They don't know that the military AND PRIVATE COMPANIES spend years and BILLIONS on research and development, most of which never makes it into production. A better widget beats it to market, a better countermeasure is developed making the thing obsolete before it's deployed (think anti-tank missiles that make a new tank vulnerable), or military contracts and support spending is used as political footballs to keep jobs in one district versus others.
I worked on the E-3 AWACS program for over 5 years. Just that one platform included radar, communications, mission computers, and other systems separate and apart from the actual airframe -- a modified Boeing 707. The technology was being upgraded constantly, and the systems had to function within the confines of the resources on the aircraft including power, cooling and space.
When a system is funded, it takes years to develop, test, modify and certify them before they can be deployed for real world operations. That's not cheap, especially when you can't run out to Walmart and pick up the parts you need when something breaks. Ongoing maintenance and parts procurement must be in place to ensure the warfighters aren't on the sidelines while their equipment awaits repairs.