yes as far as i know the ticket prices support the cost.
prices include camping. There are arts and crafts booths
and food booths which probably pay a percentage to the
festival for the chance to sell there, too.

they also sell t-shirts, and other items with the logo brand
of the fest. There is an on-site radio station at many of the
fests here which broadcasts most of the main stage artists
so they can be heard in tents and cars of those not at the
main crowd. Some fests have private, after hours concerts
in more intimate settings that require an extra ticket to
attend. these are usually indoors, and more like a night club
with tables, bevereges, etc.