Masternodes do not hold coins.
This is essentially an example of a distinction without a difference.
A user needs to "lockup" 1000 DASH in order to operate a masternode.
The DASH are "locked up" in a wallet because of said user wanting to "operate a masternode".
Gotta love the word splicing here.
Only the Instamine beneficiaries and the independently wealthy get to have Master Nodes.
The rest of us have to use Slave Nodes, over which Master Nodes have complete power.
That's supposed to be a good thing, according to Dash Logic.
The problem with that cult doctrine is that it goes against the concept, recently discovered by Nick Szabo, called social scalability.
When you raise to 1000 Dash ($18,000) the barrier to entry for running a full node (CONOP) you kill decentralization as well as the diversity of participants, which destroys social scalability.
Requiring Slave Nodes to trust Master Nodes also kills social scalability.
These two fatal flaws mean Dash is useless except as a pump-and-dump Ponzi scheme.
Of course all this is theoretical since Dash can't even scale from IPv4 to IPv6.