@Nonentitynumpty
Yes, it is a matter of belief and a third party can't prove it to you.
But if it is indeed true, it will affect everyone, whether they believe in it or not.
The consequences will also be the same for both believers and non-believers.
Acquisition of Karma doesn't depend on whether one believes in God or not, it depends on one's behaviour/lifestyle.
Being an "an okay person in life" makes sense in many ways.
But what sort of behaviour/lifestyle is okay and doesn't result in bad Karma is the essential question to be considered, according to my understanding.
Yes, it is true that people are manipulated, either on purpose or because the preachers themselves don't have a proper understanding.
Although it is very difficult to find the right resources, before following any belief, one should do as much research as possible.
The more you fall into something without properly understanding the logic of it, the more disillusioned you will be, as it seems you have found out.
All around us, we see vast differences, unbelievable injustices, "innocent" and "good" people in terrible situations, "guilty" and "bad" persons in very comfortable situations getting away with all the bad things they do.
Whatever we are is a direct consequence of what we did in our previous lives.
And what we do in this life will have consequences in future lives.
Before I get misquoted again, if we are benefitting from good Karma, it does not mean we ignore the plight of others and write it off as their bad Karma.
Callous and arrogant behaviour towards those suffering creates bad Karma for ourselves to be suffered in future lives whereas kind and caring behaviour creates good Karma for ourselves.
For me, the joint concepts of Karma and Reincarnation are a logical explanation of how things work.
If we try to isolate Karma from Reincarnation, or with what happens after death, the logic disappears as we clearly see from all the injustices around us.
But everyone is free to have their own beliefs!