First, astrology is widely accepted by young people and students, and it will spread very fast, mainly because of the large number of groups. As for the eight-character fortune-telling, most of the people I contact know this technology are middle-aged and elderly people.
Secondly, China's horoscope fortune-telling is really complicated and difficult, and it should be calculated according to the date and time of birth. A person without a foundation can't understand it at all, let alone teach himself or something. Constellations are different, just twelve constellations, and then some ascending constellations. As long as you know your date of birth, you can look it up and learn it without complexity.
Third, China has a traditional idea that fortune tellers are outdoor fortune tellers. Therefore, eight-character fortune tellers generally don't often tell fortune, because if they reveal too many secrets, they will be condemned by God. Therefore, eight-character fortune telling is relatively closed and will not be easily spread abroad.