Satoshi's motivation, even when it comes to bitcoin, is hard to pin down. There are just small information pieces, but overall they can help us understand more about him and Bitcoin.
So let's start with the most obvious. The Bitcoin Genesis Block.
A puzzling aspect of this Block: It has a secret Message within its raw hex data.
"The Times 03/Jan/2009 Chancellor on brink of second bailout for banks."
I think it can be understood as a commentary about the instability caused by the financial crisis of 2008. It also suggests that rescuing massive banks with public money, was a problem for Satoshi.
This thesis is supported by another statement from Satoshi:
"Banks must be trusted to hold our money and transfer it electronically, but they lend it out in waves of credit bubbles with barely a fraction in reserve."
There are a few other hints about Satoshi's motivations, too.
"Yes but we can win a major battle in the arms race and gain a new territory of freedom for several years."
"It's very attractive to the libertarian viewpoint if we can explain it properly. I'm better with code than with words though."
But besides this Satoshi seems to be rather pragmatic.
As in 2010, Wikileaks started to accept Bitcoin donations.
Satoshi seemed to be worried about the public backlash, although it's likely he liked them.
"It would have been nice to get this attention in any other context. WikiLeaks has kicked the hornet's nest, and the swarm is headed towards us."
I hope this will make Satoshi's motivations a little bit clearer.
Have a nice Day!