The usual argumentation is "I need to make a living" and "if I didn't build it someone else would have done an even worse job, like this at least I could be an activist on the inside and guide the efforts to make it better".
Which are of course delusional excuses when they come from anyone working at Google.
Then they'll come with "but I have a family and mortgage". No shit, so does literally everyone.
Another method is to stall and sabotage the development via endless bike shedding, language changes, rewrites, refactors. All normal things in every project. Drag those feet.