Is working too much (for money) a form of indulgence?
Buddha admire wealthy people who earn their wealth by right lively hood.
However he encourage people to use their wealth wisely for their benefit and the benefit of others.
Link to two major Suttas are:

http://www.accesstoinsight.org/tipitaka/dn/dn.31.0.nara.html

http://www.accesstoinsight.org/tipitaka/kn/snp/snp.1.06.nara.html