I never once believe karma exist and now, I still believe it does not.
There is no such thing as a zero sum game or a definite you reap what you sow, lines in novels that resonates me the most are "you can work hard, but it is the heavens that decide whether you are getting rewarded; life is unfair sometimes" and "you can do good and no one will care about you, but if you continue to do bad, then something bad will eventually finds you".
For the first line, it tells me that in most cases, the good that you do just goes down underappreciated or not at all while the second line is basically someone will be iffed by your bad move and fucks with you for certain, they ended up follows the line of "do good and no one notices, do bad and no one forgets" that has been my life philosophy since I was 13.
I don't even believe in a second life or heaven, just that life itself is a purgatory/ mini-hell for the 99% and basically we are having greek gods as moderators.
There are in certain cases to get a karma houdini when doing bad though, one, just don't blow the bad thing you do into something too big; AKA don't make people think it is more worth to punish you than to ignore you. Two, spread out your evil. Three, hide the evidence.
Subsequently, it is hilarious for those who do good and ended up being called a hypocrite by the toxic of society, I am not referring to most of those who filmed when doing charity but rather, those who decides that goodwill doesn't need advertisement and they just do it out of their heart. Before you say that sometimes their goodwill got rewarded, remember that we are more affected by negativity than positivity.