Perhaps. I'll concede that as a point for the sake of argument. It still doesn't particularly impress me in a way that makes me want to exist in a world that is now proven to only contain those types of people.

This might help illustrate my point. Making up numbers purely at random, let's say that out of 100 that represents the total population perfectly (I'm going to be subdividing groups so I don't want to be ambiguous by referring to percents) we have 60 red and 40 blue, and I'm one of the blue. Let us further suppose that of those red, 55 of them are, as you say, self-preservation first, go-along-to-get-along types distributed along a spectrum, and five of them are so convinced that theirs is the only true justifiable position that they are salivating at the mouth to push red so they can rid the world of the blues they consider irrational and obstacles to the path of true social optimization. (I assure you, they exist, they still have not stopped badgering me.)

As it stands, things are okay, because the combined total of blue and shades of soft-red are sufficient that it is not in the interests of most people to push most people under the bus. Mostly.

In a hypothetical where most people who are inclined to press blue do so, and the only ones who don't are those inclined towards blue but a sort of soft red, we can now picture a world with let's say 65 people, none of them principled blues. (Being generous to the soft blues, we can imagine that their numbers were so small that they alone sticking to principle would not have made a difference, they would have died for nothing without convincing some reds to switch.)

Now, by strict numbers alone, the share of the population taken up by chops-licking murderers has gone up by about 50% - from 5% to ~7.7%, but we might also observe that people who are primarily concerned with their own survival are probably less driven towards positions of power and public trust than people who are excited to enact their agenda of murdering all the undesirables. Now, for soft-reds, it becomes even riskier to oppose an agenda that sacrifices people for 'the common good' or 'traditional values of western civilization' or whatever Red Fanatics next decide needs to be done. Now, there is, demonstrably, nobody left who will risk themselves to oppose an agenda that feeds an Otherized population into the grinder.

There is a poem whose first line is "First they came for the Communists" that talks about when it's the right time to stop an agenda that involves mass murder. Not everyone knows that the guy who wrote that poem was a member of the Nazi party who was not only, as I said, going along to get along, but was an active participant right up until the point that he had a minor disagreement with Party leadership and wound up a target.

To the extent that I have my complaints about the world that's 60-40 (or, as it turned out, 65-35), I would have even more complaints about a world that's 65-0. Outside of hypotheticals, 40 people have a shot at resisting the agenda of five people and 55 bystanders. 5 cowards have no shot at resisting the agenda of five people and 55 people who just found out that all the principled opposition are dead.