Hi Karan,
I would suggest you to learn other modules like FIN,SD,PP which are deeply integrated with SAP PS.
Agree with you as sometimes we get very limited opportunities only for SAP PS. So better to learn other modules.
You can also think of PLM which is having wider scope as it consists of PS,DMS,PPM,QM,ECM...
Search more on PLM and you will find lot of material on this topic. Below wiki is also good which you can refer
SAP Product Lifecycle Management (PLM) - Product Lifecycle Management - SCN Wiki
Regards
Tushar