Entitlements, such as welfare, etc., is another large category of spending, possibly the second biggest, after defense. The lion's share of entitlements spending is on Social Security, if I recall correctly.
The main difference between the two types of spending (defense v. entitlements), aside from their relative size, is that entitlements spending is not entirely discretionary, but represents a contract between the govt, and the taxpayer. When you work your job, the govt takes part of your earnings as Social Security, but with the theoretical promise that this money will be eventually returned to you at retirement. In other words, social security taxes are earmarked for a specific purpose, that is, to be returned to the taxpayer. They have to be collected, and returned, that's the law.
Defense spending, on the other hand, is in theory mostly discretionary, because it does not represent any contract for the money to return to the taxpayer ever. The tax payer knows that some of the tax is used for defense purposes, and also knows this money will never return in any way. Defense spending is not earmarked, in other words. Defense dollars come from the general fund, and those general fund dollars can either be spent on defense, or on something else. There is no law that mandates a minimum level of defense spending, it is entirely discretionary. There is a practical minimum, of course, and some defense spending is necessary, at least in the American point of view (other countries don't necessarily follow suit, but the large ones do). But there is no earmarking of defense spending, and no minimum; it is entirely discretionary and arbitrary, unlike Social Security.
To reduce entitlements, which is largely Social Security, is a breach of contract, so to speak. To reduce defense spending, is not. To reduce social security, is to reduce money granted to those people who need it for food, generally poor folks. To reduce defense spending does not directly affect any individual, as nearly all defense spending is paid to large corporations. Granted, some corporations subsist solely on government defense contracts, and without those contracts, the corporations would have to lay off the workers. But even here, we are talking about the impact on merely a few thousand, or a few tens of thousands of defense employees, as opposed to millions of retired poor.
It doesn't take a wizard to understand what President Eisenhower said, that every defense dollar spent is a dollar not spent on feeding our own people, to a large degree. The old guns v. butter debate.
Obviously, the next step in this line of argument is to then discuss current defense spending, waste, and failed / nearly failed policies. But I'll stop now.
Since I'm a taxpayer, just like many, I would prefer the government not breach its contract re entitlements, and instead quit wasting my defense tax money on the family feud of some government authorities.
JMHO. You are welcome to yours, of course.
Good Luck.