Assuming, of course, that if Finland had to provide for its own defense (rather than relying on us), they would still have money left over for social programs.
Accusing Finland of not providing for its own defense is an insult to the memory of the Winter War. It's one of the few European countries that still has universal conscription!
Well, that’s OP’s premise (which I do agree with). He says the U.S. spends 700 billion/year on defense, but needs less and that the rest is spent protecting other countries. There are 195 countries, so if that’s distributed evenly, we’re contributing about 3.5 billion/country/year, that they would each have to come up with if we stopped. Now, maybe it’s not evenly distributed like that - maybe Finland doesn’t rely on U.S. presence at all (but I think you, and they, would be surprised), but the point is that we’re indirectly subsidizing a lot of these social programs by providing military defense for a lot of these countries.
One interesting fact about Finland that I learned from "The Doomsday Machine: Confessions of a Nuclear War Planner" by Daniel Ellsberg is that in the event of a "general war" the US attack on the Soviet Union was expected to completely destroy Finland and kill at least 100 million in Western Europe.
Finland has always prepared to defend a Russian attack alone, for obvious historical reasons. Russia being a superpower, or trying to be at least, means the selected defence doctrine is to make an attack too expensive to be worth it. Definitely isn't depending on US military intervention -- last time around US was siding with the Soviets, after all.