I do not think the current dump is caused by banning crypto advertisements. The market is heavily manipulated. The exponential rise in the end of 2017 was unsustainable and those who artificially pumped the market, subsequently crashed it. Now we just have to wait through the winter.
Yeah I agree. The Google and Facebook bans barely moved the markets at all, actually. Bitcoin dropped quite a bit when Twitter announced its ban though, which doesn't make sense because it's smaller than Google and Facebook. It follows, then, that the logical conclusion would be that the dip doesn't have anything to do with the Twitter ban, and likely means that the Google and Facebook ban actually had a very marginal effect on the market. Bitcoin doesn't have anything to do with ads anyway.
But yeah, massive rises are typically followed by massive dips, and here we are in the aftermath of December.