Reducing the attack to Elders means the attack is much more difficult. It is not easier. Think of it this way, a Node starts as a child, then is evaluated over time, how long depends on the networks need to scale. If a child could affect consensus then it would be weaker security actually. However as @pierrechevalier83 said nodes are evaluated, Elders are evaluated in consensus agreements, Infants and Adults are evaluated at the vault level, this means they must perform their allocated tasks and if not then the Elders punish them and possibly reduce their age. This means the “investment” of an attacker is substantial and long.
This time is very important for many reasons, an obvious one would be a botnet. If an attacker got hold of a botnet and was able to act immediately (take bitcoin as an example) then it can immediately cause issues. In SAFE though it would take a long time to get on the network, store data (many botnet devices, particularly IOT cannot hold that data) and perform its duties while waiting a long time to get to Elder status. Botnets will really struggle when the time is involved as many botnets consist of computers for short periods, for very intermittent periods (user switch off) or from low bandwidth, high latency devices. This “wait” period we have where nodes are evaluated actually makes botnet attacks very difficult indeed, relative to many other designs.,
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In terms of sybil etc. this waiting period or network decides when nodes join also means that if there are people trying to get vaults on the network then they are diluted by others also trying to join. That means an attacker with a huge number of nodes to join will dilute across the network with good nodes. 2 attackers improve the situation, by one diluting the other and so on and so forth. It is a strange way to think of it perhaps but does actually provide quite a bit of security of these types of mass attacks.
This is a really good observation. I do not agree cost is free, but hopefully, it tends very much towards that, so apart from semantics, I think we agree there. However where I am not so much in an agreement is age being only time, it is very much time spent as a valuable member of the network, so holding data, caring for it and distributing it when requested or indeed mutating it when requested and the security is provided along with the consensus of your neighbors.
Yes, they are in many ways as holders of data and processing of requests etc. The client’s though is really the one with absolute power, in that they sign to mutate data, pay resources to keep farmers interested and consume the data. So yes again I agree in many ways, but the vaults are pretty dumb by design. They cannot, for instance, decrypt data and mostly have no idea what data they have. So they are like the network drones and just behave as programmed, the humans and the clients are the real powerhouses here, thankfully.
I believe over time vaults will get smarter, but their duty is only to care for our security and data in a way that allows privacy security and freedom of all digital info for all humans on the planet. IT is probably a viewpoint and one of many, but this is how I see things, I hope it helps.