how would you build your mining farm?
You don't, buy bitcoin and hold. Wait for the next bear market to get cheap miners from those quitting the business after foolishly getting in debt during the bull. I have seen it so many times its even boring. Of course you need to move to a country with cheap electricity or perhaps even generate your own so the initial investment may not be worth it. Naturally the latest generation miner will be too expensive for a quick ROI, so perhaps a generation and two behind with the proper firmware can do the trick...
Bear market is also good to get cheap coins, so its always been a choice. Maybe use half and half or something. In any case mining is destined to be less and less profitable over time, its only the bitcoin market price that keeps extending this, there will be a healthy variance of people coming and leaving but should gradually be more and more expensive to mine. Some people even mine "at a loss" because they hold all their sats for a better market future, and have fiat income to burn in bills and whatnot. That may be an interesting long term strategy.
At this point people should have already diversified and paying in bitcoin and getting paid in bitcoin. You might as well move to El Salvador if you want this right now. Escape the fiat trap while you can, nobody can decree creating extra bitcoins when their budget doesn't fit, unlike fiat, always a time bomb...
Of course if you are going to hold bitcoin you need to learn how to do it properly, how to create a cold wallet (its a piece of paper with handwritten words aka seed) learn the process well. In the next worldwide economic collapse, those who held to bitcoin will emerge. Of course non fiat physical objects are viable as well, if you are not in a place with a hostile State that can decide to confiscate your belongings, like the USA in 1933 decreed all gold belonged to the State and you were ordered to sell it to them for cheap...
This is the other problem of a mining farm, it can easily be seized. Sadly i have seen it as well. Hiding a paper with 12 handwritten words is much easier, or the gazillion creative ways to steno-graph them so they are hidden in plain sight but you could also add encryption and other tricks into the mix, everyone should come with their own method, the State should not know, its them who destroy your wealth in the first place, inflation is the most tyrannical tax people can do nothing about. Less State, more freedom.