This is either a way too elaborate troll or one of the dumbest things I have ever read and I can't figure out which it is.

Wow you are actually serious. Okay here we go.

1. Units of measurement are made to be accurate, while most of your rant talks about "estimating". Being easily estimated adds zero value and it's something you invented to try and make your point.
2. Disregarding point 1, every single thing you said can be reversed by someone used to metric. I have no clue how to estimate things in imperial, but I can easily estimate 1 cm, 1 meter, 1 litre, 1kg, etc with a similar margin of error as you can estimate imperial, because I'm used to it.
3. Your point about temperatures is the most boneheaded of the entire paragraph. Go to Chicago, ask someone what is "kind of hot" and what is "kind of cold", and compare it to a New Orleans resident. Wanna bet they give wildly different answers? Also, again: what is the merit of this? If it's 30 degrees C outside I consider it hot, 5 or below is cold. What does it matter which numbers you find important?
4. About your rope, or your piles of grain and hunks of beef. I have no clue what your point is there. Do you know what we do when we want more precision? We just move the decimal point. You want 1/5 of a kg of beef? Might want to ask for 200 grams instead. I don't even know what kind of point you're trying to make there.
5. Metric is standardised. A metre in Belgium is the same as a metre in France, and a metre in Norway, etc. You're talking about a ounce. You mean an imperial ounce or a US ounce? Do you like pints? Do you want a US pint or prefer an Imperial one? Space ships have crashed because of nonsense like this.

As a final example, let's go beyond units of measurement. If I place a book on the table and ask you to estimate the value of it: you might say something like 20$? I might say something like €20? We just use the currency we're familiar with. What if I ask you to estimate the value of that same book in Vietnamese Dong without looking up anything? 50? 100? 200 000? I wouldn't know. I don't know if you buy a pencil sharpener or a car with 200k Vietnamese Dong. But a Vietnamese person would know, right?

You're talking purely from a perspective of someone that is very familiar with one system and has very little knowledge of the other. It's not that you -by your own omission- can only estimate something like a centimeter and not much else that the rest of the world breaks down when they see a 3 centimeter rope. Both systems might have merit, but metric is a clearly superior system in almost any perceivable and objective way that I can think of.

I have mixed feelings about measuring their wealth based on share prices because they couldn’t sell their shares without tanking the price, right?

Technically this is true, but remember that the wealthy can borrow money backed up by their stocks, so no: they couldn't sell those stocks without tanking the price, but yes: they have access to even more money because of this.

We're evolving towards the status where airconditioning is no longer optional when building/renovating a house.