fuck i hope it's not an issue, already bought a house with some of it
You're only really at risk if you get audited. But if
you get audited, get ready to pay some serious taxes. That sounds like a lot of money to hide from the IRS.
You're only really at risk of being audited if you brag on a public forum where the IRS can subpoena your account info and IP address history.
BTW, if Madoff ponzi losers get to
write off their losses, we should be able to also! This was allowed because it was considered theft - theft losses can be written off. You can perhaps write off the value of mybitcoin holdings in dollar, at the time they went poof, etc. if you want to be creative.