I think that Monero community is adamant at keeping the corrupting money away (the kind of money which could force another direction of the project). This is amplified by the fact that many of contributors are already having a steady cash flow by other means, so they can't really be bought easily. There was an interesting related question on whether the developers should be employed full time.
It is in the nature of open source projects that people just come and do what they like to do, by their own free will. Most of the worlds open source projects don't involve money, but solve some other problem, so it's hard to corrupt those. I believe it is important to keep that kind of open source spirit in the Monero community, and so far it looks like it isn't going anywhere :)
Ideally, contributors would be motivated by only wanting to solve a problem, or build and improve something, just because they like doing it. Pick a problem you like to solve, and just go ahead and solve it. If you involve money in the equation, in a way "you will get paid X to keep doing Y" then it becomes a job and it could mean you're not anymore doing what you like, but are forced to do "Y". It would suck - who wants a 2nd job like this, or even to replace the one they're currently doing just to have all this pressure from various "investors" on their back? That's why I get annoyed by people thinking they can "push" for GUI, it shows that they don't respect people's free time or the open source spirit. In the end, it is the beauty of open source that you're free to say "No".
Also consider, that if someone believes in the project and is willing to spend his time and energy working on it, that he probably loaded up on Monero while it was still around 2$/xmr. I mean, if you're investing your time in future of money, you might as well invest some of your money to capitalize on your efforts. I certainly hope that all the contributors had their bags filled before the run up to 10$.
So to answer your question: by maintaining awareness of how money can corrupt, and keeping the spirit of the project going.