I worked full time for years and now part time. My work ethic, however, has remained the same. Has to be, because part-timers as well as full-timers are subject to the same high quality assurance standards. We work part time for many difference reasons, none of which are any of your business, BTW.
Just remember, without part-timers, the full-timers would be working longer hours and many more weekend and holiday hours than they do now.
In my opinion, you are simply are wrong to blame them for your own personal dissatisfaction with your job.