This argument is made more from a hatred and FUD of "The Man" than realistic awareness of how things work.  Coinbase and Circle have insurance on accounts, and they have 2-Factor, etc etc.   I mean - your argument could be made about the current banking system - but I bet you have a bank account.  And YES - they could do a "bank holiday" and they could freeze your assets, and the entire darn system could implode overnight.  But I seriously doubt that that will happen to the replacement bitcoin system immediately.   These entities have investments from the likes of JP Morgan / Goldman Sachs.  Now that is NOT a moral argument, because of course these folks are evil incarnate - BUT they also aren't going to let there newly built little replacement enterprises be compromised.  And they won't do anything like mass seizing of funds that would make for pretty bad press, and effectively kill any chance they have for mass adoption (which is clearly their goal).

So I respect your paranoia ad your position.  I actually like it from a macro perspective.  But in the near term it is naive.  I think to protect wealth you better have a healthy mix of assets - even physical ones like gold.  But for a time at least Bitcoin will eventually take over things I think - and it sure as heck won't become the global currency based on the idealistic visions of a well intentioned, but inexperienced few.  Sorry - but Bitcoin is entering it's adult phase, and old men with lots of power and experience are now sitting at the chess table.  Better start thinking with a bit more cunning and realism.