Aren't they? I don't know much about musicians, but graphic designers are expected to bring their portfolio with them to the interview. There's no interview at all without the portfolio... and you're not always lucky enough to have all your best works paid for by someone, especially if you're just starting.

EDIT: and, come to think of it, don't musicians need to practice for a long time before even getting a chance to perform for pay?

Having family members who are all three of those... yes. They, unfortunately perhaps, are. They all have to have portfolios of some kind to prove their ability.

It perhaps depends on the specifics of the jobs you go for. For example, if you're a musician producing audio for eg film, then you definitely are expected to have a portfolio, but if you go out and play for an audience, then you probably don't.

Hrm. Musicians play because they enjoy it. Know many a people who, despite or regardless of success, will play just for the enjoyment of it.

Programming is similar. You hear the stories about how some tech founders focused their energy on programming, it took off and they dropped out of wherever.

I'd argue that for every one of those, there are scores of people who do it just for fun like they did, get nowhere but do it anyway because they like it. Just like there are scores of guitarists for your Clapton, Hendrix, etc.

Open source contributions to me look a lot like people, for the most part, enjoying themselves and getting better at a hobby.

Any business that spends $0 on marketing will likely reap $0 in sales. Think of it like marketing.