To begin with, each country has its own unique method of learning English that has been reviewed and edited by the time, so it may not be suitable for other foreigners though there exist(exists) courses or methods which are perfect for the beginners( or intermediates), for instance, Cambridge, IELTS, Oxford, etc.
Secondly, it is true that speaking with foreigners in English-speaking countries can improve our English's vocabulary and skills quickly but the other side of the coin(another side of this advantage) is that how long we can keep up with that, can you trust them(this is a question->whether you can trust them or not), are they speaking like native speakers(a question->if they speak like native speakers) and much more so I suggest that we should only do that when we master it properly in various ways, for example, learning from Youtube, signing up for a speaking clubs or courses, etc so as to improve your English skills.
Next, when you come to an English-speaking country, you immediately find yourself at a loss to understand and follow its traditions and customs so if you are going to a country like that, prepare yourself necessary knowledge in order to overcome all difficulties in the parlance, taboo, daily activities and furthermore.
Last but not least, you may have to face financial difficulties unless you have appropriate conditions or receive a scholarship for studying abroad, etc. What you may have seen on the TV or from the Internet or from advertisements about this is only the tip of the iceberg, because there are more things for you to do in order to get through this. Also, you can be taken for a ride by scammers if you don't see through it carefully.
In conclusion, I can say that although study the English language in an English-speaking country is the most effective way, it is not the only way to learn the language. Taken everything into consideration, I suggest it is up to everybody to decide where and how to learn English.
This essay explains the advantages and disavantages of learning in English speaking country and doesn't explain the whole topic.