If you are hired as an engineer and it is not your job to provide investment or business advice then I would say that you have no professional or ethical duty r

If you are hired as an engineer and it is not your job to provide investment or business advice then I would say that you have no professional or ethical duty related to your personal private evaluation of the business merits of the project you are working on. If that is not your area of expertise then your evaluation may be wrong or you may be missing information on the bigger picture to understand the strategic reasoning behind a project. If you are highly confident that a project will result in financial losses then the only really important questions are personal: do you want to work on this project given that you think if will fail financially? will financial failure negatively impact your career later?