JP Morgan has ~$2.5 Trillion under management, annual revenues near $100B/year, and profits around $20B/year. Estonia's GDP is $25B and their annual tax receipts are about $4B/year. It's quite easy to assume that JP Morgan spends far more on security than the entire country of Estonia.
well, lets hope then that Edgar doesn't get along with FSB too well and profit from hacking estonian e-voting stays lower than price of exploit :)
and no matter how big is your budget, kidnapping/blackmailing sysadmins is cheaper :P
They got away with customer data and who-knows-what-else. I'm pretty sure JP Morgan has a bigger cyber-security budged than the whole state of Estonia, many times over. And then check the laundry list of these: http://cybercampaigns.net/
The basic truth is: we still don't quite know how to design digital information systems that can resist attacks from very persistent or nation state level actors. Even if these are air-gaped (as demonstrated by Stuxnet).