Sybil attacks are not the only category of vulnerabilities found.
As your argument indirectly points out, the problems are quite fundamental in nature and therefore won't be resolved by a random developer but maybe by a bunch of mathematicians. ( I know that the Tribler people worked on these a lot )
What you call strategic decisions are in fact choices made on a operational level. In case of your context example, this is something the adversary is very well aware of.
Some decades ago, the did not only poison various DHT-like systems but even went as far as uploading jailbait torrents to the Piratebay, ordered hits on people via the US state department and got people extradited from non treaty countries in exchange for FTA concessions.
Striking a killing blow is not in their strategic interest but might become a operational choice at some point in the future.
In this scenario, the cost/benefit analysis is a no-brainer and that leaves us exposed and controlled.
What you call strategic decisions are in fact choices made on a operational level. In case of your context example, this is something the adversary is very well aware of. Some decades ago, the did not only poison various DHT-like systems but even went as far as uploading jailbait torrents to the Piratebay, ordered hits on people via the US state department and got people extradited from non treaty countries in exchange for FTA concessions. Striking a killing blow is not in their strategic interest but might become a operational choice at some point in the future. In this scenario, the cost/benefit analysis is a no-brainer and that leaves us exposed and controlled.