it has to do with one thing, that none seems to consider, the fact that altcoin mining is very profitable, and it is added to the halved block reward, another good portion of bitcoin produced per day
altcoin miner are dumping at least 1000 more bitcoin a day added to those that are produced by the bitcoin chain already, which are 1800
this considering that there are 200k gpu that are mining and each one produce 300-500k satoshi per day, in other words there was no halving at all, there is still a dump of 2800+ coins per day...
But those coins are coming from somewhere.. It is not like those bitcoin are produced by altcoin mining. People buying the coins that are dumped during mining need to buy the bitcoin themselves. So it is basically a 1 to 1 exchange of fiat for altcoin with a slight delay in between where coins are bought and sold.
RSI analysis shows that a sale was bound to happen, probably will not go lower than 550-600 usd.
those coin are still exchanged for something that is produced, and it is very profitable, so it's mean that it will be dumped under the price at which those bitcoin were bought, because miners have the upper hand over those buyers that bought those coins that are sold to those altminer
example, a random guy buy at $650 1 bitcoin, he use it to buy a profitable coin, like etheruem, now this mean that a altcoinminer dumped his etheruem for that 1 btc, now he did it at a ratio that it is very profitable for him, so he can dump immediately the 1 bitcoin he acquired
you are missing one important thing, and that is the price of these pairs (BTC-ETH, BTC-USD, ETH-USD)
if the miner wants USD he will dump ETH for USD directly and if he wants BTC he will dump ETH for BTC directly and will keep the BTC.
he will never do ETC > BTC > USD because he will have to pay the fees twice and the prices will always be at a balance that you will never make any profit from this additional step.
at this moment:
ETH/BTC : 0.01741
BTC/USD : 605.89
ETH/USD : 10.56
in other words 1 ETH = 0.01741 =10.54 which is the same value