Poloniex is going down and it is on a lot of other coins... not only STEEM
60% stored in exchange platforms worries me a little bit, because you can store it on your STEEM account and take dividends from it, why wouldn't you transfer at least half of what you have to SP and then when you start to run out of STEEM in the exchange platform because you sold (which is a mistake) you can Power Down and suddenly you are receiving STEEM everyday. It's safer and you will get free STEEM + SBD!!
I'm just guessing that numerous people bought crypto coins because it's a hype and that they are really clueless what they bought. And/or people that are just speculating but don't have a steemit account.
Either way, you should not hold you coins on exchange platforms, it's not safe... that´s why a lot of coins has it own wallet.