“Jack of all trades, master of none” is a manufactured phrase.
It is often used to look down upon a generalist (‘Jack of all trades’) when comparing them to a specialist (‘master of one’). It also creates a deception that one can either be ‘Jack of all trades’ or a ‘master of one’. However, in real world there is a strong argument for both to coexist.
As ‘master of one’ you bring in special expertise and high levels of productivity to the table. Something that people value and would happily pay for. It gives you the freedom and confidence to carve your own path ahead.
Being ‘Jack’ provides you with diversity, versatility and flexibility. It allows you to look at things from different angles and helps inspire creativity.
Being a specialist with general knowledge of relevant fields can make you stand out from the crowd. Perhaps it’s worth trying to be “Jack of some trades, master of one.”