Not sure we can draw any specific conclusion about motivation - since there is little to go on. Isn't the obvious motivation of stealing millions pretty much enough on its own? Get rich quick overnight is a temptation that would have been enough to overcome the scruples of even the more dedicated fan of ethereum. If cheating once, with a fair chance of never being caught, could make you rich, many people would take it.
I am happy to see that ethereum folks - I have no involvement - were able to put aside various appeals to some vague ideological purity, and fight off the attacker. The ethereum community, like the US constitution, is not intended to be a suicide pact.
Following up on that thought, there are many lessons to be drawn about how to improve the design of any virtual currency. The Founding Fathers too created a virtual currency, that depended on a mechanism that did not require a central all-powerful rules, where the community has acted to protect itself and keep on growing.
Yes, freedom is key. But cooperation, and reasonable mechanisms of self-protection are necessary too. Valuable lessons for designing better and better mechanisms for cooperative networks that empower each of us, and empower freedom.