By that definition making coffee at home and taking it with you to work instead of buying is theft.

Even further anytime you make a product or do a service yourself or get a free alternative (for example, open source software instead of a close-source alternative) instead of buying would be theft by that definition.

That’s not the legal definition of “theft”, it’s not even the historical or common sense definition of “theft”, it’s some kind of neo-Capitalist Dystopia definition of “theft” that only makes sense if you’re starting from a foundation of there being a “right to make money”.