It works if you are describing a business but would not normally be used to talk about a person. But ... if you did use it about a person then people would understand what you mean. It's based on the idea of drowning and there are other phrases closely related to the same idea: Things are really tough in the world but you are "staying afloat" or "keeping your head above water" ... but then it all gets too much - too difficult - and you "go under" For example: During the coronavirus pandemic he worked really hard to keep his business afloat but then the money ran out and customers did not come ... so his business went under. Hope that helps Gordon