I took these ideas quite seriously a few years ago when I posted on the topic, and I still do, but my attitude has changed somewhat. I used to see extreme frugality as an extreme moral imperative. Since then, I realized that as you mention, high income is probably more important than low expenses. I realized that I only had a limited amount of willpower to work with, so I chose to apply my optimization pressure in favor of increasing my income rather than decreasing my expenses. (I'm still quite frugal, but it's mainly to keep my burn rate low. If things go well, I won't be like this forever.) I also realized that I was experiencing a great deal of internal turmoil from complaints from my selfish side. So I began to act on an average of the impulses from both sides: my life's purpose didn't really change, but I'm much more open to making concessions to my own self-interest.

Of course, if D_Malik is to believed, it's possible to develop quite a high level of willpower in oneself through progressively higher willpower expenditure:

http://lesswrong.com/lw/5b8/insufficiently_awesome/3z5r

Clearly this is a complicated issue. People may differ, and it's all about understanding and exploiting your brains spaghetti code. I'm thinking of messaging D_Malik and getting him to teach me his method. Then maybe once he's made it communicable one of us will write a less wrong post about it.

To end on a somewhat sad note, I've noticed a trend towards greater selfishness as I grow older. It's too bad that the trend doesn't go the other way, since old people have all the money.