New to blockchain

Hi,

My name is Natalia and I live in Finland. I'm 28 years old. I'm kind of nerdy (but not completely, I'm also brown belt in martial art called Brazilian Jiu-jitsu) and I'm interested in virtual reality, 3D-printing, drones and now blockchains. However, I'm completely new to blockchain (I know the basics, but that's if) or virtual currencies. I know bitcoin, but I have never used it - it is easier to just use credit card or SEPA-payment. It makes more sense to use blockchains to something more concrete (at least, before the tech improves)...like as social media platform or land registry/voting.

I can't say I understand the concept of Steemit. How can it be possible that someone gets over USD 15 000 just by posting? How pays that money? What if he is famous and has huge following, and every time he/she post something he/she will receive like USD 10 000. After 100 posts he/she is millionaire?! I mean, is this some kind of money printing machine for the famous? :D

Also, where the blockchain is? I understand it should be decentralized, but who runs it for Steemit? Several people, I guess. How big is the blockchain? If all these posts are saved into the blockchain - it must be enormous...

Anyways, I look forward to start using this platform. The idea behind Steemit is intriguing. This could be the next Facebook or Twitter, and I guess it makes sense to be part of it at the beginning. I just don't get it fully...