To stable the Bitcoin people also can help for the stability holding their investment for long time it is one of the most important and useful for the Bitcoin to be developed and also investment made the any type of currency to a good value so it is only needed for the development with a bitstability for Bitcoin now
It will work, bitcoin price will be more stable if more people reduce their trading activity and just hold bitcoin for long term. But it will slow the process of bitcoin economic growth, usually people invest in ICO using BTC or ETHor fiat but it seems mostly BTC or ETH. In this case the movement of capital from BTC or ETH to ICO's token or coin is unavoidable, it will create unstability price of BTC or ETH. But it is okay because the ICO project also help the development of cryptocurrency in general. So the unstable price of bitcoin is not a problem.