Answer:
You could revise the sentence above by changing scientist to science.
Step-by-step explanation:
The fact is that the noun scientist refers to the person that studies or has expert knowledge of one or more of the natural or physical sciences. Therefore, for the sentence to be correct, you should add the name of the particular scientist that is helping the lives of people.
The sentence could be revised by turning it into a generalization. Instead of talking about one particular scientist, you could talk about science in general. How science helps the lives of people. In this way, you would not need to specify who you are talking about since the sentence would imply that all the scientists in any field contribute to help the lives of people (see 1).
1) How science helps the lives of people is really neat