Are you a capitalist? The first question to ask is: do you own shares? Even if you don’t own any directly (about half of Americans do but the proportion is far lower in most other countries) you may have a pension that is at least partly invested in the stock market; or you’ll have savings in a bank.
So you have some financial wealth: that is, you own capital. Equally, you are probably also a worker, or are dependent directly or indirectly on a worker’s salary; and you’re a consumer. Unless you live in an autonomous, self-sufficient commune – very unusual – you are likely to be a full participant in the capitalist system.