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Lots? I don't think lots became multi-millionaires. Very few were involved in the ICO and fewer donated enough money to become a millionaire. That said, you are right, any long term stakeholder will keep adding value to their ecosystem which they hold a stake in, which they should do. Just like holders of Steem are encouraged to add value to their ecosystem.

Ethereum was a popular ICO then, you only need 2.5 bitcoin investment to be a millionaire now.

Ethereum ICO Purchases by size

SizeNum purchasesETH
20 to 199 ETH92860672
200 to 1999 ETH20351424999
2000 to 19999 ETH263411652188
20000 to 199999 ETH39317261740
200000+ ETH4916003973

https://blog.ethereum.org/2014/08/08/ether-sale-a-statistical-overview/

And how many of them do you think held all this time?

No idea, the ICO coin received has no from/source address record, thus cannot track list of ICO addresses in the blockchain.

That means they have actual privacy. Better than Steemit.

I believe so.