It's not nearly as hard to own bitcoins in an IRA as this post suggests. For about $1,500 and a small amount of effort, you can have a company like Broad Financial set up an IRA LLC for you, which allows you to invest IRA funds directly in bitcoins or a wide variety of other investments.
I'd be super cautious of the Broad Financial option....there are many similar companies which have come and gone....it's not easy to research them to get a comfort level with thier quality...The site doesn't even have much info about the company.
I've seen hundreds of people try this but never actually seen it work for anyone.
The challenge lies in the actual implementation. Sure anyone can follow IRS regs and set up a compliance LLC to be invested in an IRA....but the actual implementation is the killer. Who is the custodian? Who does the accounting? How do you segregate bitcoins out?
I might be wrong but I've never, ever seen it work for anyone other than the ultra rich through specialized family offices.
There is a HUGE market for these kinds of fully self directed IRAs for people to buy real estate etc. -- the reason NO major firm (like Fidelity, Schwab or Merrill) has ever done one is because NONE have been able to figure out how to do it. It would be a huge profit area for any firm who did so. I don't trust the small companies who say they have figured it out.