Let me classify those who are having more than 1K coins:
1. Satoshi
2. A small fraction of the early adopters, who refrained from cashing out their coins in 2012 and 2013.
3. Owners of Bitcoin-based business ventures, such as exchanges and gambling sites.
4. A very small number of institutional investors, such as the Winkelwii.
5. Thieves and hackers, such as Mark Karpeles and Thomas Jiřikovský.
1. Very likely. He/she was the creator of Bitcoin after all.
2. Probable. Those who believed that the ath in November 2013 was nothing compared to what's in store for btc in the coming years.
3. Of course. Gambling sites rake in large amounts of btc due to their so-called "house edge." The house always wins after all.
4. Those who believe in the potential of bitcoin may be heavily invested, leaving us the conclusion that they could possibly hold thousands of
BTC.
5. Errm, idk. If you are a part of the Mt. Gox incident, you might as well have some thousands of
BTC situated in different addresses.