On what basis can we make the assumption that full-time jobs do in fact contribute to society? In this current world it's not an easy question to answer.
My approach is: many, but not all do; use your own judgement. If you can land a job that you believe is doing a service for the society, all the better for you. If you can't, it's fair to seek alternatives.
If nothing else, they contribute to your paying for your own life, rather than the rest of society having to support you.
No to mention the increased input into the local economy.
That allows others who may be doing something more directly for society to continue doing so.