Enter the Internet. Nothing makes a rumor more powerful than having it hit the Internet and go viral. Just look at our 2016 presidential election. The Russians did an outstanding job posting rumor and innuendo about the Democratic candidate and stirring up a portion of the GOP that seized the lies of Trump and ran with them. Of course HRC was as practiced at lying as Trump but his lies gained more traction. 2016 raised tribalism to a new level and i suspect
2020 will be more of the same.
I am much less concerned about adults and rumors than I am about children. Cyber bullying is reaching new heights and causing more harm and pain than at any time in our history. It seems like every week a child somewhere commits suicide because of bullying, and the anonymity of cyber bullying fuels the flames. Kids are not being provided the tools to sort through the nonsense. Critical thinking skills need to be taught and reinforced from an early age. The anonymity of the Internet makes things worse.
Adults deal with rumors regularly. They carry them to the extreme with conspiracy theory sites. Take a look at Alex Jones and his Infowars site. It is just one of many. There is so much junk available these days it boggles the mind.
There is a lighter side to rumors. Today is a day rife with rumors for the American football fan. The 2019 NFL draft begins tonight and so the pundits are all declaring who they think will be chosen by each team, This follows months of mock drafts and parsing every word from the NFL teams. The same thing will happen with basketball when the NBA draft happens. Baseball and hockey are not quite as crazy since those leagues are not primarily fed players by colleges.
Rumors can steal a person's reputation or open the person pushing the rumor to a defamation lawsuit. There is also a point at which rumors and or gossip become propaganda - again, that is something we saw in our 2016 election. Expect to see it again in the 2020 election as out current administration seems to have no interest in curbing interference from other nations.
Be sure to check Ramana's take on rumors here.