In the past, companies required a person who is an expert in their field. However, as society has been developed, there are many changes in terms of companies' requirement and today many of the companies hire people who have many different skills. In addition, there are so many people who have many different skills besides their specialty. I think that if a person wants to succeed in their life, he should develop many different skills rather than focus only on one skill.
First, people who have ability to do many things in various fields can flexibly solve faced problems. People who are an expert on one field may be only able to solve their problems related to their field and they are less likely to try to do things that are not related to their skill because most of them have not nearly dealt with other fields before. However, competent people in various fields are highly likely to solve problems that are faced trying many things based on their experiences in various fields and thinking in a different way. During their life, they will deal with their faced trouble in such ways and it will be helpful to succeed in their business and even their lives.
Secondly, it is clear that people who develop many different skills are less likely to experience failure rather than people who are an expert only one skill. I think that developing many different skills is similar to taking out insurance since nobody can predict what will happen in the future. Even if their business are faced with sudden financial crisis, people who have a lot of abilities to do many different things have many opportunities for making money since they can move to another company that are completely different from their first one or they can start new business.
In conclusion, as I just mentioned above, people who develop different skills are highly likely to succeed in their lives in that they can flexibly handle faced problems and they less likely to experience failure.