Sent ethereum to not used address. Options?

I was going to send some avax to coinbase and accidently sent all my ether from metamask to said avax address. Metamask was showing avax on ether net and I thought that was really weird so I tried sending it to coinbase. I clicked send all and it showed that it was sending ~$20 of avax. A few mins later all my ether is in this random address. Another thing that I found weird is that it only cost like $10 in gas. I mean was I dumb for sending all first? yes. But this bug/glitch is really misleading. At first I thought there was a chance to recover it because I thought I sent eth to the avax network but quickly noticed that was not possible. The address doesn't seem to be a contract or a wallet so could I generate a private key or something retroactively?

I know it might be lost but I want to understand why I can send ether to non existing wallets? You can just send ether to any random address even if it's not active as a wallet or a contract?

I tried doing what this article did but I don't fully understand so I'm guessing I can't do that.

https://medium.com/bitclave/how-we-sent-eth-to-the-wrong-address-and-successfully-recovered-them-2fc18e09d8f6

There must be many posts like this, but I wanted to ask the experts to get a more direct answer/explanation because there's like 3 things I find weird (metamask bug, really cheap gas & non active address). In addition, the transaction happened in less than 30 secs for a really cheap gas price. Nothing makes sense.

P.S. It's a nice chunk of change so i'm willing to pay a commission since that would be better than loosing it all :)