I have read that authorities are able to track the bitcoins if they are being move illegally. For example, if a wallet was hack and also most cryptocurrency exchange would require you to show ID when you sign up.
I get that some people like this, but for me it was never the point to be honest. I never hid the fact that I owned bitcoins and I never hided how much neither. Maybe that is because I never became rich, which means that the tiny amount I have is not really a big deal, most people I know have more money than me overall, even if not in liquid cash form, they have more assets than me so that means nobody really cared about me being in crypto since I wasn't rich.
If I made like millions of dollars out of this, then maybe that would have changed some things and in that situation I may have wanted to hide my wealth, but I do not know about this, since it never happened.