A person who thinks too highly of himself:
Person was born to a rich family and grows up
with other rich people in their neighborhood.
He/She uses his/her connections to inflate
his/her social standing usually by name-dropping
and similar tactics. The family fortune reverses
and now the person is working a regular job just
like most of us. Person is now looking to get
ahead in life and is looking for investments and
money-making schemes of dubious reputation.
A person who thought he/she was a bigshot:
The person was higher up in the entertainment
biz. He/she wasn't earning good but he/she liked
being in the limelight. The person gets married,
has kids and moves to another country. He/she is
no longer in the limelight and the last time I
heard from him/her, the person was trying to get
me to invest in a business he/she was setting up.