Interesting take on proof of stake blockchains:
"Proof-of-Stake (PoS), when it was first released by Peercoin and then used by Nxt, seemed to be a solution. In Proof-of-Stake, someone's chance of getting a block depends on how much stake they have so in order for someone to get more than 50% of the forging power (“forging†is the process by which new blocks are made just like “mining†but the exact method in PoS is different so it was given a different name for Nxt), they would need to control more than 50% of the coins in existence."
cointelegraph.com/news/the-failure-of-proof-of-stake-blockchains