I mean Bitcoin become popular without any promotion except from it's supports who are constantly promoting it for "FREE". Group that collects funds for Bitcoin promotion? That sounds more of a scam to me TBH, or if not, it will not be used properly. I'm not against it, but for me, we don't need it. We don't need a central authority to focus on the marketing side of Bitcoin. After all, it's a currency, not a product or service whatsoever.
Bitcoin is a decentralized project so its developments are contributed by many people, decentralized globally. If we appreciate their development works, products, let's donate bitcoin to their donation addresses. Each well-known Bitcoin developer has a donation address and we are free to support them.Check their Github, personal websites, products they have built and if we have good finance, make donation is a good step to do.
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Let's just focus on what it is I guess. Let us, Bitcoin supporters promote it "FOR FREE". We don't need a group of people to promote it because we can do it ourselves right? Let the developers maintain it, and we as supports do our thing. 
Support must be contributed with freedom, not mandatory. Donation is for individual developer, not for a group of developers. A decentralized project should not have a centralized donation fund.