I think you do not get my point of view, I just want to know that in an IDEAL WORLD, the Electrum wallet on the computer with an internet connection is safe if there is no Malwares, no hacker's attempt etc
There is no ideal world, it is only your mind that thinks that your computer is malware free and the other 99% of the users also believe the same. And then when they lose their crypto, they have no idea what went wrong.
You aren't sure. No one is sure. Have you disassembled and intricately examined every piece of hardware in your computer to check for backdoors? Have you read every line of code for every piece of software running your computer, from your BIOS and OS through to your wallet software? Are you examining every incoming and outgoing packet across your internet connect to check for malware or data being leaked? Of course not. Therefore you have no idea if there are vulnerabilities in your system.
This is the whole point of a permanently airgapped device. It is impossible to have a completely secure system connected to the internet, but you can mitigate a lot of possible attack vectors simple by airgapping your device permanently.
I am testing out making a tail OS through USB and then using electrum through it. This can be a cost effective and better solution rather than making a computer or a mobile an air-gapped device. With tail OS, the Electrum wallet comes by default and there is no need to install any more softwares. Secondly, you can keep save that USB like you save a hardware wallet.