I am in a situation where I have been offered a non-tenure track faculty position at my current university. This is also the institution in which I did my PhD, but the tenured faculty I would be working for is not the person I did my PhD with; I have been working with them since finishing my PhD though. So I feel a great deal of appreciation for the institution and the faculty member I'd be working with.
However, there are a few issues with the position, and I am considering a competing offer in industry that seems to better fit my personal goals. I (and some mentors without a dog in the race) feel that I would grow more in my area of research in the industry job. The non-tenure track position has been very hard for the faculty to fill, and they tend to lose whoever they hire to industry anyway because industry offers far better compensation. If I accept the industry job and turn down the faculty job, I will still be working with the faculty for a few months. I am not worried about the faculty seeking retribution, or that I will be burning a bridge, especially because I have been open about other offers and my goals from the beginning. Despite that, I still feel a sense of guilt considering the industry offer, and I think that might be clouding my judgement in the decision of which offer to accept.
So the question is as stated in the title, but I can be more specific. I recognize this may not be a question that can be answered with concrete steps, but what I am looking for is how to decline the faculty job in a way that will be palatable and not seen as greedily choosing industry over what I'm offered here.