I'm a print designer. Knowing how much waste is caused by my work and how it
Life is complicated, sure enough...
My advice (for what it is worth--not much, I expect) is for you to hang on to your job. Partly, this is precisely because you quitting your job (unless you have some other very clear option available to you in a "clean" occupation) won't make the least bit of difference to the project of ending waste, for the very reasons you gave: someone else will do it, and all you will have done is put yourself out of work.
Instead, why don't you consider--and urge your colleagues to consider--"greener" practices at work. For example, designs done on computers (rather than sketched on paper) create less paper waste. (An out-of-date example, I'm sure, but I hope you get the point.) Those with expertise in an industry are in the best position to find ways to cut waste and to come up with processes (and products) that are not so bad for the environment. Find these!
And where you can't find better solutions, consider finding "compensations" such as planting more trees at your place of work--or contributing trees to plant in local park areas, or somewhere else in the world--and so on. Quitting your job may seem very noble and clean--but the reality is that you are likely to end up doing something just as bad (or possibly worse), and if you stay, you may be able to make a positive difference.