"If you wish to examine a granfalloon, just remove the skin of a toy balloon." — Bokonon (aka Kurt Vonnegut,
Cat's Cradle)
Just because I mentioned specific individuals does not mean that I agree with them. I only acknowledge that they produced an effect that propagated beyond their own deaths through the actions of the devotees they acquired while living. I might also have mentioned prophets of various religions, though I may not follow any of them.
Skilled as I am at seeing the fnords, in the MLK address you quoted, under the obvious text, lies this subtext: Is my cause not great enough that you might be willing to die for it? If you are not, and have no greater cause to hold your loyalty, then you are more a walking corpse than a living man, and unworthy of my regard. It is very similar to "Crouch down and lick the hands which feed you. May your chains set lightly upon you, and may posterity forget that ye were our countrymen." It is a recruiting speech. And every time a young black person gets "the talk", it is contradicted. According to MLK, every time black kids submerge their will in a police encounter, and come away from it alive, but humiliated, they will be dead inside until their bodies finally catch up. According to me, they will live long enough to either vote in comprehensive reform or to organize and rebel from a dearth of it.
Nonviolent resistance depends in whole upon the oppressors' general unwillingness to murder nonviolent protesters. Willingness to die only works insofar as the opposition is unwilling to kill. Gandhi's protests worked only because British forces in India were unwilling to massacre Indians wholesale. MLK's protests worked only because the segregationists were unwilling to kill in public, before the typewriters and cameras of nationally-published journalists.
If you are willing to die, and the other is willing to kill you, you would be prudent to arrange your affairs in advance, such that other people are positioned to impose meaningful consequences as a result. Otherwise, you are gifting your enemy with a tiny victory.
If you quit a job in the military-industrial complex for which you have some ethical concerns, such as one which enables dragnet surveillance, what is the meaningful consequence? Every failing of the project in recent months is scapegoated to you. The contractor hires a replacement butt-in-seat. The work goes on. Your sacrifice yields nothing. No one rises in gratitude to pay your bills. When you mention in job interviews that you left due to ethical conflicts with the former employer, you never seem to be a good "cultural fit".
Why then would anyone choose to do that?
I'll take the food and the decades. I won't go willingly to my grave, if doing so wouldn't be more meaningful than what I believe I could accomplish with the entire remainder of my natural life. Sometimes, you can't avoid it, but you should always try to not die as you work towards your goals. Don't fear death, but don't ask it out on romantic dates, either.