First of all, I don't have 10 friends.
Second, they are not well payed, well trained government agents who make a lifestyle of keeping their mouth shut. Since when did rich people and the government care about morals?
When Hitler was at large he started one of the biggest conspiracies ever and there were quite a few whistle blowers. The conspiracy you are suggesting is even bigger then that and there have been no whistle blowers that have cone forward with evidence claiming that Earth is flat and the government is hiding the true shape of the Earth.
If someone came up to you claiming that Earth was flat, then proceeded to bribe you and threaten you to keep quiet would you do it? I certainly wouldn't. Anyone in their right mind would know that the government wouldn't actually kill a whistle blower because if someone came forward claiming a conspiracy and then he mysteriously dies 2 days later then that would make it even more suspicious then it really is. You could even anonymously tell the media and the government could not punish you because they don't know who you are. There is absolutely no way to keep something like that quiet.
I am planning on studying to become an engineer and I will apply to work at NASA. At that point I will be one of the people who will have to be in on the conspiracy in order for Earth to be flat, and if I am approached by someone saying that Earth is flat then the people on this forum will be the first to know.