I think some people would argue that the blackmail is used to protect us, at least when applied outside the USA, and we can trust those with access to the gathered intelligence because they are the "good guys". We don't know what actual oversight is in place. In the USA my understanding is that Congress tasks intelligence. They say "I want a report on who, how, and what is happening in renewables in Germany" and intelligence provides it. Intelligence does not decide what to do with the report, the congressperson does. They can leak it to the press, show it to their favorite USA industrialist on the sly, send it to a favored company in another country, use it in diplomatic negotiations, use it in trade deals, etc. By splitting the responsibility for intelligence in this way the collectors of it can say they have no responsibility for how it's used and the users of it can keep their use of it and how it was gathered quiet. Where this seems to break down is with the CIA who are collectors of intelligence, consumers of it, and users of it. Supposedly their use of it has to be approved, but it seems likely that gets short circuited in the field. There must be a strong inclination to act immediately on what they know, sometimes perhaps for not so good reasons and without orders. There may be standing orders in some areas to make sure reactions are expedient and the interpretation of those orders is up to the person in the field.

Also where is the border between "good for my country" and ethical behavior? Is what is best for USA industry best for USA diplomacy? Is what is best for the USA destabilizing the rest of the world? Where is the oversight when it is decided that blackmailing a foreign leader is good for a USA industry versus destabilizing that country which may have global repercussions? Do they use computer models that tie together world stability, economics, trade relationships, military objectives, and world peace? Somehow I doubt it, it seems more likely to be "my gut tells me to...". For one thing nobody really knows how to accurately model things like economics, wars, stability, etc., because human decisions are often not predictable, self interested, or rational.

It also seems likely, given the secrecy, that there are ways to abuse the system. One Senator tasking the NSA to collect intelligence on the foreign family of another Senator would be flagged, but the NSA could be tasked to collect intelligence on a related interest of a Senator, and then the information leaked or otherwise misused. It's difficult to tell what the checks and balances are here, and many of these people are lawyers, used to convoluted arguments and justifications. The citizens have little transparency into this whole system except for whistleblowers.

Jobs are what is used to keep the populace in line. When the crowd gets rowdy take their jobs away and they'll start falling in line. This might be the idea behind increasing interest rates, to cause a recession, which takes away jobs, which tames the crowd. It might not work this time if covid deaths and long covid and opioid deaths have made the worker shortage too severe giving people more power.

Big business also has it's own intelligence systems, quite extensive ones. What they gather and what they do with it is not widely discussed. We occasionally see business leaders embarrassed by revelations, but it's not always clear where the revelations came from or if someone covertly played a role in exposing them. When you are a multinational company you are probably not always limited by USA laws. It seems likely that sexual blackmail is widely used.