If you don't use your right to vote, you cannot legitimately complain about who is in power. Even if you voted for a party who might not win, like the Greens, at least you voted and used your democratic rights, and you can complain.

Let's say only 50% of those who can votem did not vote. The 50% who did not vote cannot complain legitimately, as if they voted, they could have brought any party out there in to power, due to the numbers.

If you thought Labour and Conservative are careerists, why not vote for some one who you thought wasn't one? Why not campaign for someone or even go about creating your own party? Why not even run yourself?

If you got the power to potentionally change a system, and do not use it, then it is your own fault.