Voting is not just important because you might get the party you'd prefer in power. Many of us can go for long periods without having a good option on the ballot paper.
I have a strong suspicion that many people vote Conservative not because they want to see the poor repeatedly kicked and trampled on by Tory policies, or because they want to see our assets sold off to the private sector, or because they want the rich to get richer, or because they want to bomb Syria or somewhere else, or because they think the Saudi Arabian rulers are great and we should suck up to them. I think some people vote Conservative because they think the country is in safer hands with them than with Labour. Whist I think you'd have to be a total moron to believe that (regardless of the current perceived state of the Labour party, they'd still do a better job than the Tories), I can understand why people do when virtually all media outlets tell them that is the case and hound the opposition whilst letting the government completely off the hook.
However, there is another reason to vote against the Tories, regardless of whether you think the country is in safer hands with those born to and schooled in how to rule and that is the moveable political mood.
With the Tories in power, they can do what they want. And we all know what that is: to feather their nests and the nests of their chums and associates. Conservative policies breed divisions and distrust and fear and loathing. They breed selfishness and greed and promote money over everything else. And the longer they are in power, the longer the media report everything they do and say as gospel, the more people will become used to living in a country where the poor are made to pay a huge price for the mistakes of the rich and to keep making them richer. The longer the Tories rule, the more people will become brainwashed that the way to peace is war and become convinced that value can only be measured by it's financial cost and benefit.
Most people don't want to live like this but recent decades have allowed them to believe there is no other way and many keep on voting Conservative like turkeys voting for Christmas.