I don’t think you have to been a total utilitarian to believe in “saving lives”. That is because an increase in population is not the main benefit of saving lives, and indeed many interventions that we think of as “saving lives” may have no or even a negative impact on total population.
Population dynamics are complicated and not that well understood, but one thing we know is that reduced infant and child mortality has a negative effect on birth rates. Intuitively you could think of this is a de-risking effect; if a parent wants to ensure that at least one or two kids make it to adulthood, then many more births are required under a high mortality environment.
I’d say two things:
If you are aware of unethical or illegal behavior at the company, I would suggest raising it through internal or external whistleblower channels. For example, you could raise this to your compliance officer to to the firm’s attorneys. There are definitely internal channels available to you to report things, even anonymously. Furthermore, there are many external reporting options available to you, some of which might compensate you in the event the company is fined. For example, there are whistleblower programs associated with the SEC, CFTC, FCPA, and AML, which can pay whistleblowers up to 30% of sanctions. If you are considering seeking whistleblower compensation, I would suggest speaking with an attorney first.
As far as your specific position at Wells Fargo, I would suggest that it depends on a couple of factors. One is whether your specific role is important to enabling these scandals. For example, if you became aware of LIBOR manipulation, but are working as a bank teller, then I don’t think there is any ethics-based reason for you to resign. The other consideration is how the bank would respond to your absence. For example, if the bank were to hire someone to replace you, who would be better at your job, or less likely to raise a whistleblower complaint, or otherwise worsen the scandal, then arguably it would be better for you to stay. Essentially this second consideration asks, what is the counterfactual if you were to resign, and would that be better or worse overall?
Finally, though you asked about ethics, I would also suggest that you consider the effects of your actions on your career. For example, having your name publicly out there as a whistleblower could limit your career options in some ways. On the other hand, you probably don’t want to have a position on your resume that is later shown to have been associated with some scandal.