If you act in good faith you are not responsible for bad outcomes.
There is no "if only I had ..." You can't go back, it's a waste of energy and you can't know what the outcome would have been.
If you knowingly did something wrong try to seek atonement.
Otherwise keep contributing to the world in the best way you can.
If I don't ask these questions and put good faith effort towards these concerns, then there's an exploration that wasn't executed and an outcome that will never happen. Discovery is okay.
I do still believe I have a right to pick and choose where my talents are used. I've spent a decade plus avoiding working for any smoking brands, why can't I avoid my work being used to train military models?