there are various reasons of course depending on who & what is said. my experience has taught me that peple have low self esteem, insecure, jealousy, or just plain out mean! if someone is talking bad let them talk words are words you can hear them but dont have to believe them. only "you" can make yourself happy in life & what you do for others to spread the smiles goes a long way. you control the outcome of your day & if someone tries to interfere dont "let" them! they can be miserable all by themselves or with others like them. if you believe in God then he says pray for them. people with hate in their heart need him in their life so pray he enters & you shall be blessed even more so.