In research, should I chose to an upcoming field or should I focus on well-established field?

This question is always in my mind.

Should I use the tool I know very well or should I learn new tools?

Another question is should I work on the field I am working in already or should I move to a new filed?

Here is my thought.

Consider a field that use a standard tool to research. Theoretical researchers adopt tools like machine learning for their research. Should I shift to the new tool despite insufficient skill to do that or should I stick to my actual skill? Switching completely to the new field may take a lot of time. And, the final outcome would be either successful or failure. That can not be afford by a graduate student or postdoc or who are in their early career. Another option is to to combine with existing too. But, that too decreases the efficiency. Yet, there is more chance that your project will be successful. There is less chance that the project would become failure. Hence, I chose to combine new tools with existing tools (if possible) to do my research. But, still I have to be ready to pay the cost. I should put in much effort to learn the new tools and applying them. Sticking to the tools you already know (unless you are developing them) is is not a growth mindset.

What do you think?