Yes, it's possible for a wealthy person to deploy a fleet of nodes and participate in the peer to peer network. However, in order to create blocks and be part of the pool of nodes that are rewarded for doing that, he/she will have to register his/her nodes on the blockchain. Since only a few nodes are accepted in the registry per day and all nodes waiting to be registered compete to be accepted, it requires a very long time for this person to reach the majority of the network.
Moreover, during the race to gain the majority of the network power, his/her nodes will have to keep behaving correctly, otherwise their participation score will decrease overtime and eventually some, or all his misbehaving nodes will be expelled from the registry and he/she will have to start over and try registering new ones.
One more 'safety,' as of now, is that one account/wallet can register exactly one node and to register a node, a minimum amount of his/her funds must be 'locked' (they are automatically unlocked when the node is unregistered or expelled).
So, if anyone wants to try taking over the network, he/she will have to add and manage many accounts and many nodes at the same time.
Anyway, this is the theory, and our alpha release will try to address attack vectors such as this one.
