This question was posed by Uncle 111 inside one of the comments. I thought I would post for all to answer:
Criminals are usually very selfish. So, what made the bad Rambaldi seekers like Elena's people, DiSantis, etc., willing to die for the cause when their dying would mean they would be left out of whatever the endgame was? What was in it for them? They couldn't really believe they were sacrificing for the good of mankind. Evil people don't think that way and all of their actions show they were evil.
In television, we tend to see super villains (Sloane, Elena , Irina etc.) with rather incompetent and insecure sidekicks. The villain is the "alpha dog" with all the control, all the power. The sidekicks however, are easily manipulated and usually hold the villain up on a pedestal. Sidekicks tend to be lacking in the parental area and latch on to the villain as a mentor, a teacher, someone who can help them. Elena rendered great power, how she was able to obtain this power, we will never know- but she used the world of Rambaldi to coax people into performing certain tasks. Elena's sidekick, the man with the thick framed glasses, found that by doing Elena a service, he was serving a higher power, he had a purpose. He probably felt like he didn't have a purpose before and Elena gave him one. Like DiSantis- I don't think Elena's sidekick planned to sacrifice himself for the cause. I believe they both felt they would be with the project until the end. I am sure Gordon Dean, Ivan Curtis and the others didn't plan on death either.
As for those who did sacrifice themselves- the Irina double for instance, we have to assume that massive brainwashing and manipulation took place in order for these followers to feel that their death would contribute to the plan- to the endgame. What strikes me as odd is that these people chose to die, when the endgame turned out to be eternal life. Suck don't it?
Ohh, what about Sark? Where does he fall in this?