YANBU, luck plays a massive part. We're all privileged through accidents of birth; being born in a first-world country (or being able to live here now, for those who weren't born here) is lucky in itself.
Then there are degrees of luck for those who were born here. You can be born into a family with a lot of money, or a family with a strong work ethic, or one with a heavy emphasis on education. You can also be born into a family that is struggling financially, or one that doesn't value education etc. These aren't mutually exclusive - I grew up in a very low-income family, but one with a very strong work ethic and big emphasis on education. That's all luck; you can't choose the family you're born into, but it has a massive impact on your outcome.
Hard work plays a part, but some people have a headstart on others. Luck continues to affect people throughout life; as others have said - you can get on the housing ladder at the right time, or you can develop an illness at the worst possible time. You could be hugely lucky and win the lottery on your first try, or play it every week for your entire adult life and never win so much as £5; that's luck too.
Obviously hard work, individual personalities and determination plays a part, but it's daft to suggest that luck plays no part in our lives, or that we "make our own luck". That rhetoric seems to be along the same lines of "if you worked harder, you could earn as much money as I do", which ignores the fact that some of society's hardest workers are on the lowest pay.