Question

How can one become a world scientist?

Answer 1

No need to woory abt age !!! In today's competitive grant world, this phenomenon is exacerbated. It is dangerous to one's funding to go against the trend, and if there is a lab to support and mouths to feed, the disincentives are great. This phenomenon stifles creativity, perhaps far more than biological age does. 
While it is not frequently acknowledged either in the popular press or in scientific literature, a significant fraction of scientific discovery is the result of serendipity (or to put it more bluntly, luck). From the discovery of penicillin by Fleming to the discovery of new ionization techniques such as MALDI that power modern mass-spectrometry based proteomic research, luck has frequently played a big role. Such discoveries are generally attributed to hard work and genius, rather than to luck. Doing so gives the “genius” too much credit and luck too little.
Risk taking is where most of the big discoveries in science lie. so takerisks.
enjoy  always specially when you r  working and learn to say no
Learning to say “no” is particularly important for young faculty, who find themselves barraged with such requests, and who can easily get sucked into full-time committee duties. It is wise to step back frequently and ask, “overall, is this work I am doing fun?” If the answer is no, perhaps it is time to revisit and consider diving into a new area.
Note the distinction in this guideline from: “learn to write and present well.”
Understanding and conveying the big picture for one's work is perhaps the greatest challenge facing young scientists
That's all I can give.

Answer 2

Make sure they like science enough to be a world scientist