You're more liberal than conservative. I'm more conservative than liberal. Bless your heart, I agree with all of your points. At the end of the Cold War, other conservatives were making the same noises that you're making now. For their pains, their careers were destroyed by the people who run the current mainstream conservative movement. Let's take a look at those points of yours.
Points 1 & 2. Cut defense spending and all of the cool people will call you an isolationist. Sure, argue rationally all you want; the name will stick. Also, remember that the United States is bound by treaty to defend more than two dozen nations. That includes keeping bases in some of those nations. Those treaties will have to be renegotiated. Those nations will have to increase their own defense spending. Many of those nations have budget problems of their own. Have fun.
Point 3. Touch social spending and the cool people will call you a heartless bastard who cackles at the sight of starving widows in between gulps of baby orphan blood. Sure, argue rationally all you want; the charge will stick. Of course, this doesn't solve the money problem. Iceberg? What iceberg?
Point 4. Social Security is the third rail of American politics: If you touch it, you will die. Sure, argue rationally all you want. It will help as much as it ever has.
Long story short, the bureaucracy rules us. The administration of administrators who administer the other administers who supervise the people in charge of those who actually get real work done cannot make any concessions to reality. It would be like Gorbachev loosening the grip of Communism; one exit through the Iron Curtain and it's all over.
The Cool People will double down. They will continue to double down until it is physically impossible for them to continue doing so.