I'm a long time HN user. I work on privacy tech (as in I'm paid to work on it).

I have a Facebook account and use Instagram.

My reasons are many:

I believe it should be my choice what happens to my data, and don't particularly care if Meta has the parts I share with them.

I don't believe advertising is intrinsically evil, and in fact I think it's probably been a net-good for society.

I think Meta is a better steward of my data than ISPs or telecoms.

I use Muse to read X for me with a burner account, since I want to follow certain topics but don't want to use X. It posts digests a couple times a week to a discord channel I gave it access to. It's fine and I think there are plenty of ways of using it that give essentially nothing to Meta in the way of data. Still I wouldn't recommend it to any of my non-technical friends, since I think the natural progression with these things is to just connect more and more parts of your life to them.

I said the same for years after smartphones came around.

In my book, if you use a Smartphone that's either Android or iPhone, I can't take seriously the claim that you value your privacy.

Privacy is a continuum.

Almost all of my tech worker friends use Instagram. It's almost universally used. I never talk about it because anything positive about any Meta property on this site gets downvoted. It's been like this for years and only gotten worse over time.