There must be some reasons for learning a language. Everybody has their own reasons. Around 100 to 110 million people speak Persian throughout the world. If you think that it is not too many, you are wrong because the German language has as many speakers as Persian in the world.
The Persian language enjoys one of the oldest and most complete language cultures in the world, prevalent in the three countries of Iran, Afghanistan, and Tajikistan. Anyone who learns this language is familiar with this great culture and its customs. The Persian language, as one of the four classical languages in the world, has many advantages; it enjoys a very rich literature with a world-wide reputation; and as it has some similarities with some languages in terms of vocabulary and alphabet, learning it is linguistically easy. Persian poetry and literature are also well-known worldwide which is a great motivation for learning this language. It is noteworthy that according to many surveys, Persian speakers have a particular interest in their own language, and this sense makes them to always behave well the individuals who are trying to learn Persian.
On the other hand, many big companies in the world have business relations with Iran and there are people who intend to learn Persian to be more successful in their business. Some of these companies also pay good salaries for those who are fluent in Persian.
Those who are interested in studying in Iran can also have a better chance to get admissions from the universities by learning Persian. There are numerous universities in Iran in the fields of engineering, medicine, paramedical, etc. that easily accept non-Iranian applicants who are fluent in Persian.
Contrary to some, Iran is one of the safest countries in the Middle East, many tourists travel to Iran each year and visit the historical and cultural sites in various cities. Many Persian-speaking immigrants also live in different countries, so interacting with them can make learning Persian even more enjoyable.