He that walketh with wise men shall be wise: but a companion of fools shall be destroyed. -Proverbs 13:20 (KJV)
"Recognize the fortunate so that you may choose their company, and the unfortunate so that you may avoid them. Misfortune is usually the crime of folly, and among those who suffer from it there is no malady more contagious: Never open your door to the least of misfortunes, for, if you do, many others will follow in its train... Do not die of another's misery.” -Baltasar Gracian
Derek Halpern advocates using Marie Kondo’s KonMari method to declutter toxic people from your life: “While a lot went into my success, the fact that I cut these toxic people from my life is part of the reason why it was all possible. Because when you start from nothing… you have insurmountable issues that prevent you from succeeding. You don’t have access to resources. You don’t have access to connections. But what no one talks about is this: If you finally beat those odds, the people who will be there to DRAG YOU BACK DOWN are those toxic people in your life.”
Robert Greene wrote about this in his seminal work, “The 48 Laws of Power,” with the 10th Law, “Infection: Avoid the Unhappy and Unlucky”: “You can die from someone else's misery—emotional states are as infectious as diseases. You may feel you are helping the drowning man but you are only precipitating your own disaster. The unfortunate sometimes draw misfortune on themselves; they will also draw it on you. Associate with the happy and fortunate instead.”
Further analysis is available here and here.
From Andrew Henderson, the Nomad Capitalist: “Eliminate Everything That's Not Working For You”
It’s really simple: Do you want to be happy? Associate with happy, positive people. Do you want to be rich and successful? Associate with rich and successful people. Don’t know of any? Use your brain, and find them.