I guess first of all, I'd say the concept of 'career capital' is complicated: it's less that people have 'high' or 'low' capital, it's more like, the work you've done gives you career capital for other similar work? So people who have worked for many years - which admittedly isn't everyone! - probably have career capital in some arena. I used to think that I didn't have any career capital of the sort that would be useful for "EA-like jobs", but that turned out to be untrue, and I've heard other stories like this: there are lots of ways to do impactful work. This isn't to deny that some things look more 'impressive' to more people on a CV. 

Second, a core idea of EA is that if you live in a richer country, you can have a big impact through donations to effective charities, even if your salary (and the proportion you donate) is relatively modest. Again, this doesn't apply to everyone, but if the "average joe" lives in a richer country and makes a decent salary, I'd propose that they just donate. 

Another action you could suggest to pretty much everyone is to advocate for EA ideas. Perhaps they aren't in a position to run a health charity or solve alignment, but maybe someone they know is. Older people can be particularly influential here, as they might be in mentorship roles to younger people and can expose them to ideas they might not have heard otherwise. 

Community building, operations, personal assistant roles, and general volunteering for new EA non-profits. I don’t think any of these roles are necessarily “lower expected impact” than roles that are only accessible with better career capital.

Online community building is particularly accessible and can be done in a voluntary capacity.