An old expression
that denotes an inability to keep perspective
when one is striving for power. (Political, financial, personal, whatever).
The idea is that you become overwhelmed with the pursuit and lose sight of those around you
, usually resulting in loss of respect, friendship, family, etc. aka: tunnel vision
Also the name of the autobiography that John Dean wrote after the Watergate scandal in the Nixon White House.
Closely related to another old expression:
Power corrupts, and absolute power corrupts absolutely.