1. Bounties & Bounty Hunters: During the Bull run bounty hunting was at its peak and all the bounty hunters participated heavily in twitter campaigns. Most of the tweets had some basic condition to add a few hashtags related to cryptocurrency I think that was the reason why the graph looks so tall during the bull run.
Bounty hunting is a dying industry in Cryptocurrency fewer and fewer people are participating in the bounty campaign, and there are only few ICO now compared to what we have in 2017 and 2018 the decline is pretty obvious
Bounty hunting contributed to the popularity of Bitcoin and Cryptocurrency in the past and the only way to get back the popularity is when the market is up again and heading to another all-time high, I like it more if Bitcoin's social media presence is because Bitcoin is reaching another milestone.
Think it's basically dead at this point, with there being like 5% of how many campaigns there were a couple of years back (early 2018, the crowdfunding boom period), and some of that traffic can definitely be contributed to those people.
Not only in the Twitter but in the whole Bitcoin market itself as the continue bearish market performance shows that the interest of the people in Bitcoin is really diminishing as if it is not then the bullish is has been long started.
Maybe the #bitcoin become popular in the year 2017 and we know in that year bitcoin reach its greatest price which is 20000$. Talking about the bounty, there are new bounty campaigns right now but not all are sure to achieve the hard cap or even the soft cap that's some bounty hunter get tired on joining. Lastly, there are still bounty hunters that active in participating bounty campaign and most of bounties have social media campaign which have facebook and twitter. Maybe the #bitcoin might become trend again once we new upcoming price on the market.
I still think the biggest contributing factor are the price movements, and media attention it's received. Of course, more people would be talking about cryptocurrencies when it's going up to 20,000, or dropping to a 10,000, and right now the prices are just pretty standard, stable, and could almost be described as boring.