If you are good in any sector you can earn a lot! The large charities pay a lot of money to get the top teams in... imagine some of these charities are dealing with budgets of millions they aren't about to let some £30k a year muppet muck about are they!?

I'm not sure I'd feel that comfortable taking home a lot (in the corporate sense) of money from a charity though considering the money donated is for a cause, not padding someones pay packet.

End of the day, most (if not all) charities run like businesses. It's sad but true because otherwise they wouldn't be able to afford to do the work and continue making that difference. Small charities might be able to work with volunteers but as charity size increases so does budgets and teams. Not to mention the it'll end up becoming a full time job rather than something you volunteer time for several hours / days a week so having a second job for income will be out of the question. And although some of the wages do seem high considering it's a charity it's still a small percentile of their overall income and they still earn comparably less to someone else a similar position within a corporate company.