Ripple controls what nodes are used on their network (validators). Can you run a validator? Sure, but note that Ripple, and thus the network, aren't going to use it anyway [validator]:
> At present, Ripple (the company) cannot recommend any validators aside from the 5 core validators run by Ripple
As I mentioned in another comment tree, this is a distributed network, not a decentralized one.
XRP current has no useful use cases. Institutions experimenting with Ripple are not using the public network but their own private RippleNet, which does not use XRP tokens [ripplenet].
* "6.2.3 Team Ownership: The team stake retained by the team is a minority scale."
Currently, 38 of the 100 billion total XRP is in circulation [marketcap]. The developers were "gifted" 80% of all XRP upon its creation [distribution]. Ripple and its owners still hold the majority of all XRP.
Don't know much about Ripple...