It would be fairly trivial today, for example, to attack the network by building a bunch of Amazon nodes for a few minutes of time… overwhelming the network with nodes that deliver value to the attacker, fake confirmations, etc. You’d only need to spin up those nodes for a few minutes to do an immense amount of damage.
Farmers, on the other hand, derive value over years of service. You cannot expect them to react quickly.
Bitcoin is comparatively safe because the cost of “spinning up a bunch of miners” is very prohibitive. The cost is deliberately made harder, so that Bitcoin miners cannot have real utility - but provide safety. I think it’s obvious that “proof of resource” is cheaper to forge than “proof of work”.
But does that matter? Is that really what MaidSafe is for? Heck no. MaidSafe is, ideally, a reliable and affordable replacement for protocols like “http”. The need for this is enormous, and the growth potential is huge. I would never disparage SafeCoin. But just don’t be under any illusions that it competes somehow with PoW coins like BitCoin. It is not a “store of value” … it’s a “store of resource value”. Which is limited, but still very valuable, and probably far more valuable than its current pricing levels.
Someone clever could probably come up with a maximum valuation model that computes the cost of a 75% attack vs the reward of that attack using commodity cloud services.