The most important attribute of this system is that accounts don't matter. I personally have over 1000 accounts, though most of them sit completely unused. It is (and was when I was mining) necessary to have many accounts for mining (for example, if you look at the mining queue right now you will see a couple of people now mining with many accounts each). Apart from mining, anyone can create as many accounts as they want using the cli wallet, although they do have to pay for them.

So, in summary, don't be too shocked, nor too concerned about it. SP is what matters, and the person who claims to have 30K accounts (and probably actually does) has relatively little SP. But it also means that statistics about what percentage of the accounts are active, own what percentage of the SP, earn what percentage of the rewards, etc. are always quite meaningless.