You need just follow the main rule of investment in cryptocurrency: You have lost you money by buying any coin. And also you don't need to hold all the eggs in one basket! Life will be easier if you follow this simple rules.
Yeah, Diversified your investment to minimize the risk if other currency will dump and you may recover your lose to other coins. This is a good advice which I think applicable at any market situation. You just need to invest on those project with good reputation.
Yeah it is good idea you can split your investment in different coins and you may be able to recover your deficits in rising coins. But dont even think of quitting crypto market. The money you lost will never be recovered. You should stay here and try to trade in affective way so that you return your lost money. It is important for your trust in cryptocurrency.
Only those who have no goal, does not know what they want or know what they are doing are the people who will just give up for no reason or for some reasons best known to them.
Investing in cryptocurrency is risky and it brings a risk of its own which is something everyone should always understand, and as long as you understand the volatility risk and you are able to handle yourself in each case, then you will be able to make better decisions and even be patient than to end up giving up and regretting it later, which is one thing I am sure will happen if care is not taken.