No. There are countless examples of people who have become fluent and have even mastered the Spanish language without having lived in a Spanish-speaking country.
Many polyglots have become fluent in several languages without having ever visited the countries where those languages are spoken.Nowadays, the internet has changed the way of learning languages.
If you wan to become fluent in Spanish, you can:
1) Look on the internet for a conversation partner who wants to do a language exchange
2) Watch grammar videos on YouTube.
3) Do phonetic exercises. You can follow the instructions of an expert on accent reduction on YouTube.
4) Find a pen pal to correct your mistakes (Italki, Lang-8).
However, there is a widespread idea that the only way to become fluent in Spanish is to go abroad to learn it properly. Many people believe that going to a Spanish speaking country to learn Spanish is like taking a magic pill that will solve all their problems with the Spanish language. Unfortunatelly, it won´t.
POPULAR MISCONCEPTIONS ABOUT LEARNING SPANISH ABROAD
First, I will absorbe the language like a child does. Many think that the only way to learn Spanish is going to a Spanish speaking country and immersing themselves in the language.
The problem with this idea is that they are not children. Children learn in a different way than adults. Children are not afraid of making mistakes whereas adults are. Children learn the language in a social environment, where there are lots of people who act as “tutors”, people who want to teach them and interact with them, parents, other family members, teachers, etc.
For adults who go abroad it is not always so easy to find those “tutors” who will help them with their Spanish
Second, “if I go abroad to learn Spanish, native speakers will correct my mistakes and in a short period of tiem my Spanish will be flawless“. This is just another misconception.
Most Spanish people will be reluctant to correct your mistakes for several reasons. If they do not know you, they will not want to seem rude by pointing out your mistakes. If they are friends with you, they might correct a few. However, correcting mistakes is hard work, it is not easy to correct a mistake on the spot (if you do it, the communication stops) and sometimes the native speaker will not be able to detect those mistakes in the middle of a conversation.
Third, “I will learn the language just by immersion in the Spanish language 24 hours a day.”
Although living in a Spanish speaking country may provide you 24 hours a day of immersion in the language and culture, learning Spanish does not only consist in listening and speaking. There are other areas like grammar and writing that also need to be learned.
There are people who come to work in Spain, interact often with native speakers and greatly improve their listening skills. However, they return to their countries and they still make a lot of mistakes when they speak.
Some people come to Spain and work as English teachers for 8 hours a day. As a result their students learn English, but they practice their Spanish skills very little. In order to take advantage of living in Spain, you should have a job where your interactions take place in Spanish, not in your own language.
Nevertheless, going abroad to learn Spanish might be a very good idea if you do it the right way.
ADVANTAGES OF GOING ABROAD TO LEARN SPANISH
First, if you go abroad and live with a Spanish family or you live in the house of a Spanish teacher, you will have a lot of interactions with native speakers and you will improve a lot. It is very important that you make friends with native speakers exclusively. All your interactions should take place in Spanish.
People who come to Spain to try to master Spanish, or even to study other subjects taught in Spanish, will improve enormously, and this kind of immersion is one of the best methods to master a foreign language
Second, your listening skills will improve very quickly, because you are forced to understand what people tell you. https://bit.ly/2HJdbRl
Third, you will learn a lot about our culture. You will learn the language in real situations and that is priceless.
When you go abroad, your brain makes a leap. You wil be in a foreign country, a different culture, and you will have to get used to using the Spanish language 24 hours a day.
You will have to use the language in different contexts. You will learn how to order a coffee in a bar, to ask for the bill, and to carry out other small tasks. That knowledge is invaluable. Because a language is a communication tool. When you talk with your teacher or your conversation exchange partner, it does not matter if you do not understand everything they say. But if you are in a restaurant and ready to order, you had better deliver your message correctly or you will not eat what you want.
Going abroad is not necessary to reach a very high level in Spanish.
However, it is absolutely necessary if you want to use the language in context, in real life situations.
Language is a tool for communication. When you go to a Spanish-speaking country, you use the language in real situations, with real people and with real consequences.
If the police asks you for your passport, you need to understand them to solve the problem. Nevertheless if you go to the internet, you will see quite a lot of polyglots who have never been to a Spanish speaking country and who are able to speak it at a really high level.
So if you have the opportunity to go abroad, it will provide you with real interaction, a better knowledge of the culture and lots of confidence when you use Spanish.
However, if going abroad is not an option for you because of time, money, etc, it is possible to learn Spanish to a very high level without having to live abroad.