Most only for personal reasons it seems.
Check it out:

The National Security Agency has quietly released more than a decade of reports detailing surveillance activities that potentially violated U.S. citizens’ privacy rights.

Covering NSA activities from mid-2001 to 2013, the heavily-redacted reports document possible abuses, including instances of employees emailing classified information to unauthorized recipients or issuing “overly broad or poorly constructed data queries that potentially targeted” Americans.