The reason why Bitcoin isn't as volatile this year is probably due to many people engaging in long-term investments and we haven't seen as many transactions recently compared to the past years.
While holding to trade in the bulls and other purposes with regards to holding might account for some percent of the observation, I think another place to look at is the price of Bitcoin. The price has pumped to a surprising high for everyone. I guess most of us never expected bitcoin to create the current ATH and it did.
This scares off a few others from actively investing or trading it as, you don’t want to lose value on every Sat neither do anyone hope to buy too high.