But the chance of losing your data is triple.
[because] each one gets only a 3rd of each file
I think the meaning was if you spread your data across 3 nodes, but you need 3/3 nodes to access the data then the chance of losing all your data is times three.
If you used a parity system like RAID 5 across 3 nodes, then you could lose 1 node but still access your data. Losing 2 or more nodes means all data is lost, but also means the party performing the seizure needs 2/3 servers to recover the data.