Inevstors and traders are mostly active on twitter, if you don't have much fund for Ads placement on popular omega sites. Tweet, retweet and tagging of friends might do wonder and the cost is minimal as compared to placing Ads.
I would say that an SEO expert would be better to handle this. There are traders and investors on twitter but these are mostly the low to mid-cap traders apart from retail investors. Bigger names in venture capitals do not waste their time investing on stuff promoted on twitter or so because they know that majority of them are worthless with time.
What they do to raise capital is sent prospectus to the bigger capital funds and set up a meeting where they discuss a lot of under the table deals. That is how the "advisors" are taken in. They have a lock in period and they will sell their coins after that. It is bad for the market but good profit for the bigger funds.
Another point is that social media buzz is often manipulated and inorganic, so the real engagement ratios might always be fake. Proper growth of a project happens through development and proper marketing, not just ad placements.