There's a story in Masters of Doom where Carmack and Romero do just that. If I recall correctly, they would take company (Softdisk I believe) computers at night because they were more powerful than their home computers, and use them to develop their own games. I think they even worked on their own games on company time. I might be getting the details wrong on that one, but sounds like Carmack dgaf (or just doesn't think about how these things could potentially be wrong/misaligned).