Trid: It's sad, but some ppl are just like that, and there is nothing you can do about it. :/
In a way there is.
You can decide to not let this change your ways. Every time in life (as that's a lot of time) where you get scammed or worse for having tried the right thing, for having respected the other ones too much, for having seen things from a different perspective than your own bellybutton's, you have the temptation to go "never again, fuck them all, if this is how it works then this is how it works, i've learnt my lesson". And you become the same asshole as them, with the same excuse as them, and you give the same excuse to the next one. And you, indeed, more efficiently protect yourself. At the expense of endorsing fully the planet's shittiness (beyond justificatios such as "ah i wisj it was a different place but assholes force me to be an asshole).
So, what you can do is fight back this temptation. And send the world to hell by
not adapting to it. By not letting assholes convert you to their self-fulfilling prophecies. And by accepting the cost.
The only gain there is to keep the contempt outwards, and to keep the right of criticizing their behaviour. It won't have the same snowball effect as evil does, it won't make you a happier person, and it will probably make you a less successful person. But at least it won't excuse, in hindsight, the cheats.