The United States Secret Service was originally created to:

TheUnited States Secret Service (USSS)was originally founded in1865to combatcounterfeiting, which was a significant issue post-Civil War. The agency later expanded its role to include:

Financial crimesinvestigations.

Cyber fraud detection and prevention.

Protective services for high-ranking officials(added later).

Today, the USSS plays a key role infinancial cybercrime investigations​.

References:

U.S. Secret Service History and Reports

Financial Crimes Investigation Manual

McAfee Institute Cyber Crime Investigator Training