Alternative would have been for them to give their riches away and stay true to their beliefs. Oh, maybe they were just skin-deep/ thin veneer Marxists. Do you suppose??
Lenin was a wealthy enough fellow, his dad was a substantial landowner, a member of the local gentry, attained through his own efforts, daddy Ulyanov was a self-made man. Russia had quite a lot of social mobility in the late 19th-early 20th century.