Hazrat Usman rah would have given away all his wealth if it was forbidden.
We should all try to seek knowledge and work as hard as possile in order to become part of the global trade.
Hazrat Mohammad pbuh did the same, and worked with the richest people (Hazrat Khadeeja rah for example) of his time and in the process became rich as well. All the while he pbhuh was known as sadiq and amin.