By this logic, any instrumental action taken towards an altruistic goal would be “for personal gain”.
I think you are making a genuine mistake, and that I could have been clearer.
There are instrumental actions that favour everyone (raising epistemic standards), and instrumental actions that favour you (making money).
The latter are for personal gains, regardless of your end goals.
Sorry for not getting deeper into it in this comment. This is quite a vast topic.
I might instead write a longer post about the interactions of deontology & consequentialism, and egoism & altruism.
(I strongly upvoted the comment to signal boost it, and possibly let people who agree easily express their agreement to it directly if they don’t have any specific meta-level observation to share)