Informants are often compensated in a variety of ways. Maybe you get some cash or maybe you avoid arrest or torture in exchange for giving up someone else. Or maybe becoming an informant was a criteria for government sponsorship in academics or sports or to keep their position in a high profile career. Although some informants just do it for ego or ideological reasons. Is your neighbor annoying you with their late night clandestine meetings? Rat them out! It's unfortunate that these records don't include reasons as to why someone became an informant and what information they actually contributed, if any.

There are several Chinese informants caught in the last few years in Western countries, a lot was just doing it for ideological reasons, the monetary reward really doesn’t match the troubles involved and the severity of the crime

That information may come in spring when the B files drop.

Many became informants because they were approached by agents asking them to tell them everything they knew about a target. Pretending to not know anything was risky. If they discovered that you didn't tell them about something you should have known, it was your ass that got sent to a re-education camp. If they as much as suspected that you were withholding information, you may have found your job suddenly relocated to some forgotten corner of the country.

If you think, i'm exaggerating. My grandfather, a prominent writer, was exiled to teach elementary school in far-off village for a few years after one of the ruling elites decided that his latest play was unsympathetic to Communist ideals.