Are all bitcoin wallets already created or not?

Question

bitcoin

Hello. I did the following experiment:
Downloaded Electrum >
created a wallet there >
turned off the Internet >
on the "Receive" tab clicked on the "New address" button >
Received several new wallets >
opened the site https://www.blockchain.com/btc/ on another computer address/ and entered the wallets I created offline there.
And to my regret, a page with this address and a zero balance opened.

1. Tell me, do all possible addresses already exist and https://www.blockchain.com will open them or did Electrum insure itself and open the addresses that I will "generate" offline in advance?

2. And if the addresses are already there, how is the owner of this address determined? Since when do I own it and when do I not.

3. Also, the moment with the item "Expires after" is not clear. When you click on it, a message appears:

Spoiler

Дата истечения срока действия вашего запроса. Эта информация рассматривается получателем, если вы отправляете им подписанный платежный запрос. Истекшие запросы должны быть удалены вручную из вашего списка, чтобы освободить соответствующие адреса Биткоин. Срок действия биткойн-адреса не ограничен, поэтому он всегда будет частью кошелька.

For me, these 2 sentences are generally a contrast:

Expired requests must be manually removed from your list to release the corresponding Bitcoin addresses.

A bitcoin address never expires, so it will always be part of the wallet.

Are my addresses or not? My only 24 hours? Or forever? Or if no one replenished them in 24 hours, then they are not mine, but if they replenished, then mine? And if on the 25th hour it is replenished, will the money go to someone else?

4. There are such wallet addresses:

1Lets1xxxx1use1xxxxxxxxxxxy2EaMkJ
1fuLL1xxxx1power1xxxxxxxxxxzatvCK
1of1xxxxx1anonymity1xxxxxxxz9JzFN

How did they get them? I understand that it's overkill, but I'm interested in the process itself. They didn't press the "New address" button a million times.

ps I read an article on the wiki, read several articles on the net, but each time there are more and more questions. Maybe there is some book or article that will describe in detail the principle of creating a wallet and describe in detail this moment with public and private keys (why, how and why)?

Answer 1

https://vas3k.ru/blog/blockchain/
in the same place about
Ethereum, you get it simply - you randomly generate a private key for it, if you're lucky - you'll generate one that already exists)) and doubly lucky - with money)

Answer 2

1. I would single out the concept of "purse" - for non-technically trained people. In cryptocurrencies, what is usually called a wallet is nothing more than a pair of private key + public key. Any value other than zero and SECG where N is less than for the secp256k1 curve of a 256 bit number.
Simply put, any line in the hex with a length of 64 characters, except for the above exceptions, is already a private key.

0xAbcdef1234567890abcdAbcdef1234567890abcdAbcdef1234567890abcdAbcd

2. There is no reserved owner as such; it works on the principle "if you know the private part of the key, you can dispose of the funds" (or sign a guarantee to transfer the funds to another public key). The private key is static, it cannot be changed, etc., therefore, many words of warning articles have been said and written about storing it.
3. Something is not clear, most likely you are looking at a service that does not provide access to the private key or its variations like mnemonic phrases, derivations, etc. If you generate a pair of private and public keys on your side, it’s unlikely that anyone will be able to somehow influence it from the outside. In your question, I believe that you are given the opportunity to manage the funds with a public key for replenishment, but the private key remains with the administrators, then naturally they have the opportunity to manage. Or, when generating on their side, they keep the private part for themselves, so to speak, which is not very good (and for them too)
4. Transformation, from a private key, you can select a public one (but not vice versa), the wallet format is base58, for easier human perception. In fact, this is the same set of numbers, but it is difficult for people to operate with large numbers, and it is more difficult to perceive them than the shorter alphanumeric version
. How did you get it? random number within the first paragraph of this answer. You can more clearly get acquainted with the pycoin library
pip3 install pycoin
after installation, the console tool ku and tx will be available
pass any number except zero to the ku parameter
ku 123
get a pair of keys and other views with view conversion