Who do they reserve them for? Deep pockets?

Exactly. For example, two-letter .de domains are far more expensive than normal ones – which is how DB and VW got theirs.

db.de (as well as ix.de, hq.de, and bb.de) was registered before the registration of two-letter was forbidden. After a lawsuit they had to give vw.de to Volkswagen which then led to permitting all short domains. Those were given out on a first-come, first-serve basis (i.e. to those with the best resources).

For $ in pockets DO graft.fu