jack of all trades, master of none
器用貧乏で何をしても中途半端だ。
Being a jack of all trades, everything I do is half-baked.
器用貧乏にならぬよう専門を極めたい。
I want to master a specialty so I don't become a jack of all trades.
彼は器用貧乏を自認している。
He admits to being a jack of all trades but master of none.