Two pieces per machine. One on the hardware — what breaks, what it costs to run, what owners report publicly. One on what actually happened to a unit running at our own site since its launch day, computed from daily bitcoin price and network hashprice rather than a projection. Nobody pays us to write either.
Bitmain Antminer S19K Pro review — Machine review, 6/10, Sep 20, 2026. Mediocre hardware that made money anyway — if you bought it on day one and kept the coins. The launch-day unit is up 25% on everything that went into it. The same machine bought six months later, for $300 less, is down 12%.
Mining bitcoin with an Antminer S19K Pro for 3.1 years — here is how much it actually mined — Field report, Sep 20, 2026. Bought the week it launched, racked in Argentina at 6¢, run through a halving, moved to Nigeria when it stopped clearing its power. Not one sat sold. 0.1151 BTC kept, $4,209 of electricity paid, and about $1,888 up on everything that went in.
Machines are the roof, not the building — Guide, Sep 20, 2026. A mining operation is a property. The machines in it are the roof — they wear out on a schedule, and a working operation replaces them out of the income the old ones produced. Nobody calls a roof a failed investment. Here is the arithmetic of the roof fund, with a real machine that paid for its own.