Yes, Marek, you pay a lot to do it, attending all the fund raisers, dinners and lunches (all those raffles!) costs you a lot of dosh
It is entirely voluntary but carries with it a lot of responsibility. You are subject to election/re-election each year but you are limited to no more than 3 years in the job. This latter is a good rule as you can become stale and it prevents any single individual getting excessively powerful behind the scenes.