I like the 401k analogy, but also it's important to reverse the frame to challenge the very way they are thinking about it:

example:

"all the fiat you hold onto is worth so much less than when you got it, why are you still keeping your value in that? At what point do you drop something that literally only loses value persistently over time? How long until you cut your losses?"

Or similar:

"If you were storing energy in case the power went out, and you had batteries that lost 5% of its power every month for no reason, and then you had other batteries that actually gained 5% energy every month. Exactly how much of your time would you allocate to the shit batteries instead of just getting more of the good batteries?"