Because you think of buying the stake... Many exchange owners had a stake history with percentages much higher that. So if an exchange gets hacked the coin gets attacked?
Unless the exchange has more than 50% of all coins, or is the only node, no.
Doesnt look like a sound monetary system to me. You can buy old stakes keys to attack. You can even create StakeUndo service like
http://www.bitundo.com/ and gain at no cost for old stake owners.. Market cap has nothing to do and valuation does not improve or reduce the security model
Everything here is false and I already explained why, in the second half of my first post. I'm not replying to you anymore until you start reading what I already wrote on the topic.