All sorts of people do, since Mozilla's financials are publicly available. See the audited statement at the end of https://www.mozilla.org/en-US/foundation/ann

All sorts of people do, since Mozilla's financials are publicly available. See the audited statement at the end of https://www.mozilla.org/en-US/foundation/annualreport/2015/ https://www.mozilla.org/en-US/foundation/annualreport/2015/