Almost all ICOs go through what I refer to as an ICO reversal process, and its amplified in bear markets. Often times, people who get in at presale will dump bonuses to buy cheaper on an exchange, and it's often followed or paired with people selling bounty tokens making it worse. Then people who don't know better follow them by selling at a loss, or hoping to buy much lower, until the sell-off is ended by demand picking up some steam. Even in good markets often ICO projects dump first for these reasons, so it's doubly expected in a bear market and expectations should be that it dumps twice as hard and twice as long. But hopefully, a good project will bottom out and start curving out into profit with news and announcements to pair with the selloff ending and send it spiraling many X if it gets listed on major exchanges.
The best practice imo is buying at the bottom of a dump on the first initial exchange instead of buying at ICO price.. its often a lot cheaper and a lot less stressful.