Can someone who works in an industry or for an employer with clear negative impacts on society/the world maintain a clear concience?

As someone who is currently still in education for their degree looking at the current (and likely future) economic and societal outlook, it seems like employment in fields that cause/perpetuate negative issues in the world (Big Tech/Military-Industrial Complex, industries contributing to climate change, predatory sales/financial firms) continue to maintain strong employment availability and salaries as time goes on.

However, fields that have a neutral or beneficial impact on society and the world (Medical care, Food service, public infrastructure, humanitarian aid work, environmental research), either don't have enough available positions that people are able to transition into, have worsening working conditions due to poor management or limited resources, or just don't pay a living wage to most who work there.

I've read about the broken window fallacy, and I understand how focusing on personal gain without considering the impacts on the wider picture doesn't make for a better world. But can someone feel justified contributing to the "broken windows" of the world knowing that they weren't presented functional alternative pathways, and try to contribute towards the solution in other ways?