@hj yes it's better to cook for multiple people. if you live on a budget you learn to cook for much less money than anything preprocessed you'd find in a supermarket.
but yes, a lot of leftover stuff. when im especially bad off financially i sometimes make a stew that i reheat over several days.
in any case tho, cooking is kinda therapeutic. when you feel down, instead of rotting in bed you end up doing something that's ultimately good for yourself, you're treating yourself good.