Questions like these are based on a misunderstanding of what class actually means. Being working class doesn't mean being poor, working down a mine, or keeping pigeons, any more than going to college or working in an office makes you middle class. The working class is, basically, everyone who has to work for a living, and the ruling class is the people that we work for. The middle class is a small group somewhere in between the two - not rich enough to live off the work of others, but still not entirely dependent on their wages. The working class is important because of the society we live in today.
Capitalism is based on an unequal distribution of wealth and power.
A small minority of people control most of the world's wealth, which means that they own the farms and the factories that produce all of the necessities of life. The rest of us have to work for them - and this, not the clothes we wear or the books we read, is what makes us working class. At the heart of the capitalist system is profit, the difference between what we get paid for our work, and what our work is worth. In every profitable business, by definition, workers are being paid less than their work is worth. What's left over is your boss's profit, money that they've earned from your work.