Drupal is not a commercial entity, so all money used to fund things like DrupalCon (conferences) must be funded from within the community.

You can make a donation to the Drupal Association or support the Drupal Association by becoming a member. Note that you may also donate by credit card.

Drupal's infrastructure is provided by the good folks at Oregon State University Open Source Lab (OSUOSL). Consider donating to them to help keep Drupal's infrastructure healthy. See the details at Donate To The OSL.