What is the reason behind Git Access Tokens being viewable only once after generation on platforms like GitHub? I'm struggling to comprehend this approach as it compels me to store the key in an insecure manner.

The reason is that it grants access on your behalf so it needs to be handled with care. You should only need it to grant the access to whatever tool you're setting up and never again. If you need to set up again, or set up something else, create a new token.

someone is gonna snatch urs while ur making a coffee 😄

to make them visible multiple times, THEY had to store it in an insecure manner..

and you gotta store it somewhere anyway to use it.

and i really really really HOPE you have learned of a little think called "password managers"?