My personal feeling is that the high karma that you are speaking of is not a good use of time (for that reason). I know it has helped tptacek and some others but it takes considerable time (and is a distraction) to comment on HN and essentially if you do it, you do it for fun and to learn. And if something comes from it then that's icing on the cake.

I actually picked up a considerable amount of side consulting by being a regular commenter on a well known blog. While I make money from that side consulting (near 6 figures), it's actually a drain on how I make money in other ways. It almost doesn't pay (but it's fun). [1] However the time it took me to earn enough of a reputation which led (in an indirect way) to the consulting (and contacts) was really a poor use of my time.

A better idea time wise, to jump start reputation, and build a rep (in a community like HN if that is what you are trying to do) would be to attempt to do things that are remarkable and get attention. Then people might talk about you and you will have the reputation that you seek that will bring other things that you need.

[1] I also get to meet many interesting people and contacts as well.