It's an entitlement excuse.
When I was in high school, I knew a lot of kids who worked at Burger King. They were stealing money from their registers, some of them managing to lift over $800/month. Everyone agreed this was a good thing because "they didn't get paid enough." High school kids. Not paid enough. Seriously.
The only excuse for using company time for non-work is not having work to do. You get an admin job and you're efficient enough to do it in 1/3 the given time? Well, I can't rightly say you've been stealing company hours if you're achieving 100% of your assigned work. Some offices even tell you to go home if you're done your work, and pay you anyway--they're legally-obligated to pay your salary if you're exempt, just like they're not obligated to pay overtime, so if you work 15 hours and get all your shit done and they send you home you still get paid. That actually makes sense.
What doesn't make sense is agreeing on and accepting a salary and then stealing time, money, or equipment from your employer under the claim that they're not paying you a fair wage. There is no fair wage. Market rates are rates people can't manage to push up from and employers can't manage to push down from. Businesses employ the lowest bidder, and employees go with the highest bidder. You took the bid? You agreed to this shit. Excuses like the distress of unemployment and the difficulty of getting a job just tell me you wanted to fasttrack the process and get bumped to the front of the line and you bought the front spot--that's what your lower-than-industry-average salary is: a privileged purchasing agreement.