To decide when to stop mining coins, you need to
consult your spreadsheet that computes profit.
I thought it dropped below profitable, a couple
months ago for Bitcoin (depends on rig efficiency).
Although more than a few of the operators, are
sentimentalists and mine coins past when it makes
sense to mine them -- for speculative purpose.
That would be people with a couple GPU cards maybe,
not corporations sporting Intel mining rigs (the
latest thing, is Intel makes a rig for mining coins
and competes in the same space as BitMain).
If the coins fall in value today, you mine your butt off,
so when the price triples again, you can make
your profit from speculation rather than mining as such.
Or at least that's what you tell yourself, while
ignoring the spreadsheet you're supposed to be using.
You don't have to mine, to speculate. You can just
buy coins when you feel it's hit "rock bottom", and
ride the wave back up. To speculate, you don't need
a GPU or a BitMain/Intel box.
Like levitation, those coins just randomly ride back
up again, when "fundamentals" do not predict such.
Back in the old days, you would buy one Bitcoin (because
at the time it was worth $3), and then promptly forget
where you left it. Later, when it's worth $10000, you're
constantly looking about the room "is it under sofa cushion ?
Did I leave it in shed ?" and so on :-) You never get
to recoup your joke investment, because you
did not take care of it. Nobody wants to be reminded
of that Bitcoin they bought and lost.
Paul