I work(ed) with a lot of Phd's, none of them earns more than I (Msc), except when successfull in sales or management.
For an academical career, pharma, medical,... it's the only way to progress, for all the rest I would advise to look at your field of intrest, and aditionally study something else, useful to get those things done.
Your "Power electronics" projects can benefit from knowledge in Law, Big data, patents, mechanical design, hydraulics, Network security,...