You're a little confused if you think 20 mill would take the price over 1000.

Our friendly whale who put in about 4 mill brought the price up from $1XX to $148.90. And thats with a few more million from other people. So, 8 mill -> $40

But 20 mill [and lets say, 40 mill] -> +900? Dont think so.

Of course if your friend grandma is braindead and clicks market order 20millUSD, then yes, around 10kUSD/BTC spike.

There must be a reason most mega-wealthy people have bothered to put a couple million into bitcoin.

That's my guess; the whale(s) are buying about a million $ a week.  That's probably all that they trust on Gox at one time.  The pullback on Gox is pretty natural after the kind of runup we've seen, OR maybe it is just that arbitrage is finally happening.  This whale put up that wall at 135 because that was his average buy in price.  He put it near the money.  HE WANTED it to be eaten.  He WANTS coins. 

The whale is NOT supporting the price during the week.  He is happy to disappear for a week and hope the price goes down.  This is the behavior of a real long term investor...

Right now, I think it is very risky to sell.  But at the same time, there's lots of coins being mined and in theory these ASIC owners need to sell to recoup their investment.  There may be a large hidden ask at this price and this whale is only eating half the generated coins per week... but of course there are a lot of smaller investors adding demand.

Don't you think that the only reason for BTC exchanges not to offer this facility is because they're all playing there own markets?  I can't understand it otherwise.  If your commission rate is based on volume and tied to price, you'd think they'd want you to trade often.  I can put a limit order on buys at Bitstamp but because I can't stop loss I don't do it overnight, so they lose those trades.  It doesn't make sense to me that they would turn down that margin unless that's not there business model.  Profit comes from manipulation - the commission fees are just gravy.