Most people have a rather narrow understanding of the concept of martyrdom and it’s effect on the course of human history. When asked about it, the majority will mumble something about Romans throwing early Christians to lions.
While Wikipedia defines martyr well enough, it does not go into significant detail about their outsized role in human history.
A martyr is somebody who suffers persecution and death for refusing to renounce, or accept, a belief or cause, usually religious.
I would alter that definition to include people suffering significant personal loss for an unpopular cause.
Let us start with the role of martyrs in the establishment of religions..
Take Judaism. What would Judaism have been without Moses? Assuming that his story is based on a real historical character, it is very obvious that he left a pretty good gig in ancient Egypt to lead a few thousand argumentative people on a multi-decade camping trip in the Sinai desert. Let me rephrase that- he left a pretty cushy life to do and ultimately die for what he believed in.
Or take Gautama Buddha, a prince with all the trappings of luxury and wealth just giving it up to look for the meaning of life. We have Buddhism because one really rich guy decided to just give it up and become a monk.
Then there is the case of a liberal Jewish rabbi whose Crucifixion created a new religion which many of you are familiar with. He could have saved his ass by being less controversial, but he evidently chose otherwise.
Islam has two main branches- sunni and shia. The shia branch exist because this Husayn ibn Ali became a martyr at the battle of Karbala. That event and its fallout still affect the world, especially in the middle-east. Sikhism is a religion about Martyrdom.
Secular religions also have their martyrs-
Even 400 years after being burnt at the stake, Giordano Bruno’s memory is still invoked to criticize religion in general and Catholicism in particular. He could have chosen to be more diplomatic, but he didn’t- ultimately making him one the biggest PR nightmares for Catholicism. Spinoza could have chosen to follow in his father and become a rich Jewish merchant, instead of a heretical philosopher. Ignaz Semmelweis could have chosen to not press his theory about infections, rather than tirelessly promote it to a uncaring world. Robert Oppenheimer could have just become another businessman like his father or remained a somewhat famous professor rather than do something which made him famous, controversial and ultimately a martyr in the american communist witch-hunt of the 1950s.
Leonidas could have stuck a deal with Xerxes and saved his life and about 300 others. Thich Quang Duc could have chosen to die of old age, rather than immolate himself. His sacrifice was the beginning of the end for american designs in Vietnam. Killing Martin Luther King Jr just ensured that he is now seen as a saint, or as close to one as secular ideology allows. It is hard to argue that those 19 people caused more direct and indirect socio-economic damage to the USA than traditional adversaries with ICBMs.
People who believe in a cause strongly enough to suffer or die for it are often far more powerful in death than in life.
I should note that all of these events occurred in the era before mobile phones, ubiquitous internet, Facebook, Twitter etc. Imagine the effect of some of these events in our world.. or just remember what happened in the Middle-East because some guy set himself on fire.