Those who diversify too much run the risk of being a jack of all trades and master of none.

那些过于多元化的人可能会面临成为万事通、一事无成的风险。

The expression " a jack of all trades and master of none" is an old expression to refer to people who are able to do many things a little bit.

“万事通，无所不能”这句话是一个古老的表达方式，指的是能够做很多事情的人。

This is a criticism – a negative statement about someone – if you say " She is a jack of all trades and master of none." " Trades, " here, simply means different skills.

这是一种批评——对某人的负面陈述——如果你说“她是万事通， 但一无是处。 ” “行业”在这里只是意味着不同的技能。