I think every person is different, for me personally I don't care about a specific number but rather the individual use-case of a project. I try to select projects that already have existing customers. With that being said, at the moment I don't see a scenario where bitcoin tanks and doesn't bring down the rest of the market. The market is not mature enough to differentiate projects based on intrinsic value, as a a consequence "diversifying" has little value... for now. In the future that will obviously change.