Every month, your employer transfers Bitcoins into a time-locked address that can't be transferred out before you reach retirement age. You have the key to the address. You can verify the transfer on the blockchain.
No middle-men. No funny business. No brokers with pyramid/eyeball shaped logos. No "oops we went bankrupt and lost your retirement." No bail-ins. No raising the age of retirement.
Just Bitcoin.
I'm sorry, but that's a terrible idea. Bitcoin is much too volatile to be used as a retirement investment. Don't get me wrong, I love Bitcoin. But it's not the right vehicle for a retirement account.
But just because it is too volatile now doesn't mean it wont be stable in the future. If bitcoin is the worlds first international currency adopted by billions by the time people are ready for retirement it could be a great plan.