Bollocks. Nothing to do with not being bothered. If you vote, you're giving them a mandate. What would happen if they threw an election but nobody came?
Sometimes, withholding your vote is the right thing to do. Other times, you have to vote to make e.g. Nazis lose their deposit, but there are no acceptable real candidates, so you vote tactically for the MRLP or whoever.
"democracy is the worst system in the world, except for all the others."
The wording is 'all the others we've tried'. It was never intended to be a statement that FPTP parliamentary democracy is the best we can come up with. The basic idea of democracy is to give everyone an equal say in decisions, but no system used in practice has actually achieved that. Personally I think the thing to do is to turn voting rights into property and allow people to sell them ;)