I could make more money than I do right now by doing things I believe to be unethical. Should I? If I shouldn't, why should someone doing what they believe to

I could make more money than I do right now by doing things I believe to be unethical. Should I? If I shouldn't, why should someone doing what they believe to be unethical things not take a paycut in order to stop doing those unethical things? And why should we not criticise those who do unethical things for money?