Is it common that the last author gets all the credits when the work becomes hugely successful? Whenever I read news about some scientific breakthrough, names that come up are mostly of the group leaders, a.k.a. last authors. I believe in most cases, it is rightfully for the last author to get the credit. The first authors are usually inexperienced Ph.D. students who work under the guidance of their supervisor. Ideas from their first author papers mostly come from the last author, and they often only implement the ideas.

However, there are certainly cases where the first author is also the idea provider. Who will then get the credit when the work later becomes a huge success? How can the public then determine the contribution? What if the paper one day is considered for a Nobel prize? I am thinking about the CRISPR-Cas9 papers. It is speculated that the two last authors will be awarded the Nobel prizes. How about the first authors of that papers?

Note:  A Nobel prize here is just an extreme example that popped out of my mind during writing. I want to talk about more common situations where the group leaders go around the world and give talks about an innovative work, whose idea might actually came from a student. He might give the student full credit but in the eyes of the community he is still “the one” simply because the student is just a nobody.
There is no absolute way of assigning credit for a really groundbreaking project.  Depending on what is known of the laboratory dynamics where a discovery occurred and the roles of the specific individuals involved, sometimes graduate student contributors get a large part of the credit, sometimes not.  Here are a few examples of how things can play out, drawn from the list of Nobel Prizes for Physics:


The 1996 prize went to David Lee, Robert Richardson, and Douglas Osheroff for their discovery of superfluidity in He-3.  Osheroff was the graduate student who was doing most of the experimental work.  The original goal of the experiment was different, and Osheroff was the person who realized that they were seeing something very interesting and unexpected.  Because he was felt to have made a key intellectual contribution to the laboratory work, he shared in the Nobel Prize and other accolades.
The 1993 prize recognized the discovery of the Hulse–Taylor binary pulsar, which could be used to measure orbital energy losses due to gravitational waves.  Russell Hulse shared the prize with Joseph Taylor, his dissertation advisor.
In contrast, when prizes are given to the work of very large collaborations, such as in the 2017 prize for LIGO's observation of gravitational waves, it is only possible to recognize the top individuals in the research collaboration—those who are felt to have made the key strategic decisions that led to the discovery.  Most of the junior contributors in such a large collaboration are doing work that, while it may be quite important, is only a relatively small and technical part of the project.  So the 2017 prize went to the three top (surviving) LIGO managers:  Rainier Weiss, Barry Barish, and Kip Thorne.
Other times, even when the groups are smaller, sometimes it is felt that the driving force behind an important experimental accomplishment was the head of the laboratory.  This was the case for the Nobel Prize for Physics in 2001, given for the achievement of Bose-Einstein condensation, in two labs, one led by Wolfgang Ketterle, and the other by Carl Weiman and Eric Cornell.  Both groups had numerous graduate students, but the faculty leaders were felt to be predominantly responsible for the key design of the experiments, and so it was Ketterle, Weiman, and Cornell who got the Nobel Prize.


Moreover, the graduate students working on these projects, even when they are deemed by the scientific community to have been relatively minor contributors to the most groundbreaking results, can typically count on successful careers ahead of them.  Working a Nobel-Prize-winning (or otherwise widely recognized) project is a real advantage for one's academic reputation.  I personally knew most of the people in Wolfgang Ketterle's lab when he won the Nobel Prize, and they generally enjoyed very successful careers in either academia or industry.

Sometimes, however, there are still some recriminations afterward, in situations where graduate students may feel that their contributions have not been adequately recognized, and this can still be a real problem.  I think that for a long time, there has been a growing understanding of the importance of the contributions of the people actually performing the benchtop lab work that may lead to a discovery, but the situation is still by no means perfect.


For example, Cecil Powell was awarded the 1950 Nobel Prize for Physics on his own, for the discovery of pi mesons.  At the time, prior to 1960, the award was not given except to the heads of laboratories, meaning that the post-doc Cesar Lattes, who designed the photographic emulsion that observed the first pions, was left out of the prize.  He did, however, have a very distinguished subsequent career, and was one of the foremost members of the scientific community in his home country of Brazil.
Even more egregiously, Anthony Hewish claimed credit for the discovery of the first radio pulsar, even though he had initially dismissed the discovery by his student Jocelyn Bell Burnell.  Hewish got half of the Nobel Prize for Physics in 1974, but Bell Burnell was shut out.  However, her contribution (and Hewish's unethical behavior) did eventually come to be understood in the scientific community, and she has enjoyed a career as one of the most prominent astrophysicists in the world.