Wait a sec.  This makes little sense to me.
- Bitcoin doesn’t care who owns it.  
- People are allowed to use their property however they like, including opting out of janky, cumbersome, accident and hack-prone, highly-taxed custody solutions for ETFs behind tax advantaged wrappers.  
- Few of the first19.5 million of mined bitcoins are in ETFs.  What is the eventual ceiling for # of Bitcoins in ETFs?  Probably not that high.
- Bitcoin is global.  If the US Feds stole and parked Americans’ Bitcoin, prices everywhere else would skyrocket, including in enemy countries. How is that advancing US interests?
- If the US Feds sold Americans’ seized Bitcoin abroad, it puts them in foreign countries’ hands, some of them enemies.
- Bitcoin is now protected by Wall Street’s armies of lawyers and lobbyists who would fight such a seizure of property almost the way through SCOTUS.
- How does stealing Joe and Jane Sixpack’s retirement funds, including their target date retirement mutual funds,  earn politicians votes?  It does quite the opposite. 

 I agree with most of what you've said but question a few of your assumptions. 
Why would taking Coinbases BTC make prices skyrocket? 
What makes you say they'd sell it? Fort Knox is still loaded with 6102 gold.
Why didn't Wall Street or the supreme Court stop FDR in '33?
The gold theft wasn't branded as theft. Everyone got $20 an oz for it.  

 Thanks for the discussion.  My imperfect understanding is, FDR seized the gold because the dollar was backed by it at the time, yet citizens were attempting to trade in their dollars for gold during the Great Depression.  The govt could not keep up and tried to outlaw private ownership of gold.  That kind of prohibition didn’t work and, eventually, the govt  recanted. 

 It looks to me like the same thing is going on. As the dollar keeps dropping, more will trade their Dollars for Bitcoin and may try and outlaw private ownership. I wouldn't stay they recanted but 40 years later, Ford repealed it 

 Fair point about the SCOTUS not stopping FDR.  I don’t know.  There must have been more of a consensus then that it was necessary. 

 As for taking the institutions’ Bitcoin, it might have the same effect as the estimated 4 million lost or frozen Bitcoin today.  It means that fewer coins are available to trade, as if the 21 million is effectively even far MORE scarce.  The sudden increase in scarcity would be a supply shock in the rest of the world. 

 Fair point. It took a few decades but that's exactly what happened to the cost of gold in USD 

 And NGU, including for enemy HODLRs like Russia, Iran, North Korea, etc.  Policies that would enrich our enemies seems highly counter productive to US interests to me and, therefore, unlikely. 

 Right. So what makes you think they'd sell it off? 

 The US?  If they stole and then HODLed, the supply shock would, logically, skyrocket globally, probably recking many even weaker currencies.  

That would not be a popular move at all and there would be pressure to sell to pay debts and meet spending without raising taxes.  One can imagine campaigns based on the idea.

This is entirely speculation of course.  The global political economy is a wildly diverse and unpredictable system.  But I don’t default to “The Feds are going to steal all the corn and that’s the end of it.”

Everything in this inflationary world is good for Bitcoin. 

 I believe we're in agreement 🤝