I don't think that crypto currency has any negative impact on global economy.
Now a days most of countries has bad economic conditions because trade war and cold war in Middle east.
As per some reports, I have read that There are some few percentage of people who know about Bitcoin, and there are very small % of people who actually own crypto asset. We cannot compare bitcoin with world economy until there is equal participation in crypto from all countries.
We don't discuss the effect of cryptocurrency on the world economy anyway. we discussed about the bad economic conditions will make many people then adopt bitcoin or not. I think people will certainly look for another currency that is safer than their fiat local currency, which is very vulnerable to inflation when the economic crisis occurs, of course the first choice is gold, because they have a stable value and tend to rise. I think cryptocurrency will not be the first choice for this case, but I am sure that even when the economy deteriorates, many people will definitely adopt bitcoin so that their economy improves because of the benefits.