I think the argument you’re really looking to contradict is this: if 1% of a company is worth $1B to somebody, then somebody would pay $100B for the whole company. That does not follow (and indeed the acquisition price of a company is almost never exactly its “market valuation”).
The acquisition price is almost always significantly more than its market value. The reason is that if you start buying shares on the open market each transaction of yours will raise the stock price, and eventually you will price yourself out of the purchase.
So what buyers do is negotiate directly with the board and propose an inflated price that >50% of shareholders are okay with.
You are assuming that the money that I buy the sweet shop for is what I evaluate the value of the sweet shop to be worth. That's not necessarily true.
You're also assuming I'm not insane.
If I offer to buy an apple from you for 1 trillion dollars because I believe consuming that specific apple will make me a god, that apple is not actually worth 1 trillion dollars.
If I have an apple and you agree to buy it for $1T, then the apple is indeed worth $1T at that moment.
After the purchase is complete it is worth ~$0, or whatever the next person is willing to pay you for it.
Alternatively you can say “it is still worth $1T to me” and that would be true as well.
When we are specifically talking about companies, their value is where buyers meet sellers in the order book.
Are you selling me just the apple?
Whether someone else will share your judgment of its worth is highly unlikely, but it is also entirely irrelevant. Worth has never meant "objective value to literally everyone."
I think your definition of value / worth should be based on the seller, not the buyer.
There are contracts that involve exchanging $1 to satisfy some legal requirement of consideration, but the relationship created is worth much more than $1. And of course there are barter transactions where items are exchanged directly without any specific valuation in money involved at all.