In a community where instrumental rationality is high-status, there will be social pressure to behave according to your stated utility function. So you have to be careful to at least state a function that's sufficiently compatible with your real one that people won't notice the discrepancy. If they do, they will try to help you overcome your "akrasia".

Note that I said "compatible", not "similar". So your real utility function could be "complete selfishness". If complete selfishness requires support from a rationalist community, you may wish to signal cooperation by stating that your utility function is "complete altruism".

The result of this is that you will find doing lots of world-improving stuff (to keep the support of the rationalist community) , and your true selfish utility function will ensure you have lots of fun, find lots of sexual opportunities, etc. while doing it.

I should have mentioned the "stated" vs. "private" distinction in the above post. I'll write these ideas up in a future post, but I'll probably need to explain a bit more of my view on signalling first.