The best argument that Doge is a scam is that they didn't start with the Pentagon. All federal agencies are audited every year, they even each have an office of non partisan experts that compile this yearly and continually look for fraud and waste. The Pentagon was ordered to complete and audit by Congress, and given several years to do. They failed for more than 10 years to provide ANY numbers (aside from the Marines that made stuff up). When they finally completed their audit in 2018, they failed to justify the numbers for 7 years in a row. They currently can't tell where more than 50% of their funding is spent. That will now be half a trillion dollars. The first thing Trump did was fire all the expert people that audit federal agencies, and then exempt the Pentagon. One agency, that consumes nearly half of the federal annual discretionary budget, can't tell us where they spend more than half their money. This is what most people call a scam.

Because the military was buying his products and wasn't standing in his way of making profits with pesky things like safety standards, and "not poisoning the environment"

Easy, because it was NEVER about actual government efficiency, it was about gutting major chunks of the Federal government, especially ones that might hold him accountable.

Because he wasn't under investigation by the military?

The unproductive nature of "defense".