I expect the money will come from Wall Street once adequate custodial / regulatory framework is in place.

I agree, I think the last bubble was when everyone was talking about it. Everyone wanted a piece and people were buying bitcoin hearing about the massive gains. I guess that's when the whales took profit.

The focus now by the whales to broaden the ~~sucker~~ buyer base via the ETF's.

The blockchain buzz has also been correlated to the bitcoin price. Both seem to have gone done.

It could be a little of both additional supplies of late-to-the-party money have finally found their way to this market, amplified by the ongoing process of coin concentration into fewer and fewer hands. Both factors (with a little help from breakage and block reward subsidy tail-off schedules) constrain liquidity and thus drive up the price. But it makes for a very distorted "market cap." Fiction, leavened by just enough fact, feeds an eager fantasy, which feeds back into more fiction. Last one out the door gets to hold the very real bags.