A country of 5 million people with mostly a tourism based economy.
Our Costa Rican economy is, more than ever before, based on providing services: customer support, technical support, financial services, web and games development, digital arts, ecotourism, etc.
See that's a force that has a daily purpose unlike a standing Army that waits for battle.
The 70-something strong UEI is something most countries have since the 70s to fight terrorism, like Germany's GSG9. Again, not a standing army to fight another army.
A standing army on the other hand is a very large and very powerful tool, either to fight outside armies or to impose internal repression. The whole point about abolishing the military was to take this force out of the larger equation. The UEI will never be a threat to Costa Rica itself, a standing army would be.
In my native Germany you can consider a chunk of the Bundeswehr to have a right-wing/extremist mindset (E.g. Franco A.) and I wouldn't trust it much in a situation like say a Green-party leader becoming Bundeskanzler.
Per capita investment will be the same whether the population is 5 million or 50 million.