If you are that paranoid then you might want to hoard some gold and/or silver coins, I guess. Or a bunker full of supplies.
You don't have to be paranoid. A solar flare or CME can easily take out half the world's electrical grid for months and even take years to get back to 100%. If that happened to a developed part of the world (Europe or North America)... the vast majority of wealth would be inaccessible on powedered down computers.
What's that? You think I'm nuts...
http://en.wikipedia.org/wiki/March_1989_geomagnetic_storm parts of Canada were without power for MONTHS.
The one in 1859 took out large portions of the telepgrah network
http://en.wikipedia.org/wiki/Solar_storm_of_1859I don't think you're nuts. I do think there are probably systems in place to guard against this. Large banks probably synchronize their data to disaster sites... so if the northeast US got hit, they could very likely operate from their DR center in say, Arizona.
Who keeps large amounts of money sitting in the bank anyways? Invest it! A solar flare wouldn't wipe out the fact that you own property, or a business, or even stock - again provided the exchange in question had adequate DR facilities in place which I am sure they do.
If a solar flare hit that was big enough to impact the whole planet, then we would have bigger problems than worrying about whether our checking accounts and/or bitcoin wallets were affected.
You don't seem to understand. 1 solar flare or CME can take out the electric grid for a hemisphere. The damage could range from inconviencing a small area for a day or two to destroying major components of the electric grid causing continental blackouts lasting many months to years until enough tranformers can be replaced, at best you'd have rolling blackouts for large portions of the country within months and full restore not for years. This could happen at any time. Offsite backups for banking data DO. NOT. MATTER. If there is no electricity for months or longer. Most large American cities only have enough food in the groceries to last DAYS, cities like Los Angeles have LESS food than that on the shelves. Knock out power to a large portion of the u.s. via a solar event and inside a week people will be looting. If it happens during winter or the middle of summer you'll have the sick and elderly seeing a mass die off the first few days, in a month you'll likely have lots of dead rotting in their homes simply because emergency services and undertakers can't get to them to deal with the remains, this would cause more deaths from the spread of disease.
To get power restored, you'd need China to co-operate and their factories to start providing the necessary infrastructure... how are you going to pay them, you have the U.S. producing NOTHING. They might not see payment for several years. Bet lets assume they agree to ship them as fast as they can make them, and other countries start shipping over food and personnel for humanitarian effort, the U.N. steps in and handles crowd control. You are looking at 6-24 months or MORE to get the power grid back in a worst case scenario (which is still a quite probable event, sun regular has CME's and flares, they just happen to be pointing the wrong direction most of the time)... so you see 300-350 million people be reduce 10-20% just from exposure in the winter and/or summer. Hell, every single person on life support is dead in the first few days as hospital generators run out of electricity. If it took 2 years to restore the electric grid to what it was at you might see a 50% reduction in U.S. population from starvation/disease/exposure/person on person violence... all because the sun decided to aim a CME/flare at the planet one time.
Doesn't have to just be America either, could be any country or continent in any part of the world.
What good are 1's and 0's on hard drives going to do you without electricity...