This is interesting topic. I think any good ICO should know how to manage this. Some ICO pay in ETH they as well can place a buy order with that ETH and mop up from hunters . when bounty campaign starts its always very % of the coin they are given to hunters that can be handled
Holding altcoin is the best to do in order to maintain the value of the altcoin so that many investor invest to that altcoin. But after that you can't convince to the people to still holding their altcoin especially when times the value of that altcoin goes high then the value of that altcoin goes down and it is normal. It's all about supply and demand of the market if we are talking about the price, when people are buying or invest the altcoin price will goes high because the demand will rise but in the other side if people selling their altcoin the supply will rise so the price of the altcoin will goes down.