Nope, your analyses are off.
The Costs to mine gold, are based on human payroll , equipment costs, petroleum to run the equipment,
all of which have variable factors.
This means the price to mine gold can increase or decrease , but the final decision is always , is the mining currently profitable.
In BTC, Miners with older rigs always stop mining, no more than 2 years after purchase, as the ASICS are no longer profitable.
You confuse a running network with bitcoin earning a profit.
So are you saying that bitcoin mining hardware degrades over time and gold mining hardware doesn't?
PoW miners go bankrupt all of the time,
And businesses go bankrupt all the time. What's your point? Bitcoin mining is a competitive business and industry just as with other industries.