Some popular sayings i combined: Evil is smart but kindness is naive, It's easy to give into evil but being Kind is hard

I'd say kindness may be naive. It can also come from wisdom.

Or strength.

From a personal experience there's a learning curve. You start off being kind to everyone. Then people take advantage of your kindness and they get ahead, so you get angry and start being evil, then you realize that's getting you nowhere. Then you learn to be kind to most people but also know when to be evil.

According to game theory, tit for tat is the most effective long-term strategy.
know when to be evil? i am assuming you meant to say when do we have the right to defend ourselves?
- No I mean you know when it's beneficial to be evil. There are moments in life where it will be better for you to do something "evil" that will benefit you and no one would know about it. Sometimes it would be stupid not to, but because morals are so socially ingrained a lot of people wouldn't do something considered "evil" even if no one would find out about it. I think thats stupid. So in my opinion you learn that you have to be kind in 98% of interactions, but occasionally you will come across situations where being evil will be more beneficial than being kind. Being smart enough to know when a situation comes up is what I'm talking about. Defending yourself if never evil, it's self preservation. Never evil

A malaphor!

A malaphor is a blend of two or more idioms or phrases into a single expression that ends up being nonsensical, confusing, or amusing.

Some popular sayings I've smashed together: "Don't count your omelettes before putting all your eggs in one basket."

Bonus saying: "We'll burn that bridge when we come to it."