1. Most of the great things that have been done throughout history have been done by people who put more effort into their work than most. People who are absolutely average and normal achieve much less. It is doubtful if there is one major reform, for example, that has not required a at least one person to work "excessively" for it.
2. People who work excessively but love it and thrive on it are not workaholics, although they may be a bother to their friends and relatives.