10. Yellow smiley faces
Who would have thought that a simple yellow smiley face could could gain this much popularity! It all started back in 1963 when Harvey Ball drew a happy face for his PR company’s client, State Mutual Life Insurance. Sadly, he never trademarked the icon, and only received $45 upon selling it to the client.
Enter brothers Bernard and Murray Spain, who instantly recognised the unrealised potential of the smiley. After a year and a half, the duo made $50m. They later sold their business to Dollar Tree for a hefty $500m.