"fool me once, shame on you; fool me twice, shame on me" Fake "wisdom." Self-shaming isn't productive.
"you get what you pay for" "used to say that a thing that can be bought for a very low price probably isn't very good" -- merriam-webster.com
"time heals all wounds" "used to say that feelings of sadness, disappointment, etc., gradually go away as time passes." -- merriam-webster.com
"nice guys finish last" Actually, "kind, emotionally sensitive, and caring about others—holds great appeal" --from linked article
“whenever you find yourself on the side of the majority, you should stop and reflect” Attributed to Mark Twain
"So live your life that the fear of death can never enter your heart" Attributed to Tecumesh, Native American Shawnee leader (1768-1813)
“The pen is mightier than the sword” The exact phrasing dates to 1839, but "the idea of communication surpassing violence in efficacy had numerous predecessors" --Wikipedia