And, in rare cases board members can be held responsible for the actions of the board. In that sense you have a lot more to lose as a board member than as a shareholder.

So if you think that the board might be held liable by shareholders for something in the future it is usually a prudent step to create as much distance between you and the board as a shareholder as you can so you don't end up on both sides of a lawsuit.

Is that true? Many people are on multiple corporate boards, and some boards meet only a few times a year. I've only been on charity boards, but it wasn't a particularly demanding commitment.

I guess the reputation cost is a good point, but Kalanick is always going to be associated with Uber, whether he's officially on the board or not.

In a public company there's a real time commitment -- not just regular meetings, but committee meetings, etc.

That said, its more like a 5-10hr / wk commitment, not a full time job.

What kind of commitment? Can you give concrete examples?

http://jayshah.me/2018/01/05/board/ (and discussed at https://news.ycombinator.com/item?id=16108235)

Reputation is usually something that affects you regardless when you are on a board. Plenty of board members invest little time or commitment, though.