In Spanish class I am learning about Costa Rican culture, and as part of that I had to do some research about Costa Rica's neutrality and absence of a military. However, I couldn't really find that much satisfactory information. Why is it that Costa Rica, a country surrounded by many other unstable Central American countries, has been able to abolish their military and (seemingly) have no consequences?
Ever since the Costa Rican Civil War of 1948, the country has been relatively stable with (mostly) good leaders who have instituted a series of reforms that have brought a degree of economic prosperity to the country. While many other Central American countries were embroiled in civil wars and coups d'etats during the second half of the 20th century (often instigated by the US, i.e. the Guatemalan coup of 1954), the Constitution passed following the 1948 civil war guaranteed the right to vote to women and blacks, abolished the army, and diverted funds from the military to education and infrastructure development. This has led to a very high rate of literacy in the country, one of the highest in Latin America. Coupled with a large amount of investment in the country, especially by US and German companies, this has led to a relatively stable society - los ticos (Costa Ricans) are consistently rated as some of the happiest people in the world. They also have one of the most developed health industries in the Americas (it is often rated much higher than the U.S.'s, and they spend much less of their GDP on health care than we do), and the average life expectancy of a tico (79.3 years) is the second highest in the Americas and higher than that of the United States (78.6 years).
There are also not many countries that would be interested in attacking Costa Rica. Although they don't have a military, they do have a Police Force and the United States has a offered to defend Costa Rican if someone were to attack them (but again, there is not much cause to).
As to your point about the civil wars in neighboring countries, many of those wars featured conflict between indigenous populations and peoples of European descent (mestizos). Thousands of Mayans were executed by the Guatemalan government during the revolution there, because they were suspected of aiding the rebels. Due to the geography of Costa Rica there was never a large native population in the country, and even after Spain colonized it there was never any massive migration of people to live there. This lack of conflict between settlers and indigenous people reduced the need for a large military relatively early on in their history.
tl;dr There are not many people who would want to attack them. Additionally, following their own Civil War many people were suspicious of the military (and militaries in general, after seeing what was happening in neighboring countries). By abolishing the military and diverting the funds to internal development, they were able to increase the quality of life to such a high level that a military was no longer necessary to maintain peace internally.
I can find sources for you if you'd like, I don't have time to find them at the moment but I've read quite extensively on the subject through my coursework at university and would be more than happy to dig some up for you later. If you ever get the chance to visit Costa Rica you most certainly should, it is an absolutely amazing country and is in my top 3 that I have visited.