It depends on the way a astrologer understand and interpret a horoscope and his knowledge.
Astrology is also a form of study and science the only need is to understand and interpret it properly.
"It is hardest thing in the world to be good thinker without being a good self examiner"
Here's one experiment we did. I used my cousin's kundali to find out about his future.
1. Astrologer one : Took no money from us. Astrologer said, He'll have a lot of wealth till his age of 70. He'll get good wife and end up in happy family.
2. Astrologer two : Charged 500 Rs. He said, my cousin has some business issues and he may lose a lot of money. His family life is going to be good. And everything will be normal.
3. Astrologer three: Charged 1000 Rs. He said, cousin needs to do puja and stuff in order to get rid of dosha of some planets. And he is having woman issue (in reality my cousin was the problem not the woman). And he also suggested expensive pujas to get rid of dosha.
Reality : My cousin committed suicide in 2010. And he had financial issue. Family issue and also lot of other problems which were not mentioned in the kundali. So you can guess almost every jyotish we take the kundali to is basically not even sure if the subject has any life line upto specific point. So any speculations made by them is as good as conspiracy theory we read online or newspaper.
My sister at the age of 29 had divorce and almost every jyotish we went to told her that she'll not remarry and may suffer a lot in future.
Reality : My sister got married at 36. She is settled in US and has a child.
In short never ever believe in Kundali for your marriage, finance, job, kids and future. You'll be fed lies and hopes and speculated cooked up stories.
Only thing I didn't tested as of yet is Nadi bhavishya thingy going on these days. Lot of people think it is true but I kind of doubt it. I will try that one out.
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease
This is not only in hindu mythology that horoscope is there. In other countries also this is there in some form or other.
Now coming to the authenticity of this. Scientifically speaking, astrology does not come in the category of physics, chemistry, astrophysics, astronomy, biology etc. However It can be categorised with palmistry type of methods where unfortunately a lot of subjectivity is present.
It is very difficult to accept that astrology predictions will be true in all cases even if every record of birth is correct.
My intention is not to offend someone's belief but these things more go in belief rather scientific base. It is like homeopathic medicine - it may work, it may not work.
Knowledge is power.
The more stake one has ,the more faithful, believing and conforming one becomes.
Beggars does not have much stakes except the need for next time food. He has nothing to lose and only to gain.So he ill not have any faith in astrology or some similar maters of faith and belief. However a producer of a big budget movie has a large stake. So he will try to visit an astrologer, get auspicious time to start, conduct puja etc.
Personally though I do not visit astrologers for anything and everything or refer all the 'this week for you' columns, personally I am of the opinion that astrology can give some hints about our future. This is so if the horoscope or janma kundali is cast correctly, is interpreted by a well experienced astrologer who doe not compromise for gains.
A knowledgeable and sincere astrologer will first counter check and verify correctness of the horoscope. There are many methods for that. Only after that he will go for interpretation and prediction. One should not believe those who predict by just having a glance on the horoscope. It needs many laborious calculations, eliminations and filters.