In the sense that they will only put in a finite amount of effort (compatible with profitability), and take everything they can get. Over years, the amount of effort or technological means might increase, but it’s not like they operate with the singular focus of collecting everything about everyone.

Right. They don’t care about having data about “you” in particular, they care about having enough data about enough people to sell ads effectively.

Marketing to you doesn’t make them money. Marketing to many, many people roughly like you makes them money.

You yourself are only a tiny and statistically irrelevant piece.

This is only really true of marketing campaigns, and even then only in some instances. In certain kinds of marketing (e.g. direct campaigns), there may be downside risks to casting too wide a net beyond just cost vs profit.

It's also important to understand that these data aren't just used for shotgun marketing campaigns, they're also used in highly targeted applications. For example, if you give a company a small amount of information about yourself, for example through a insurance or financial services "estimate" page, that company has very good reasons for wanting as much (and as accurate) data about you as possible. The two biggest reasons are:

1. If they're smart, they're running models to associate those and other things with purchasing behavior. Notwithstanding the fact that they need to stay on top of the model's accuracy, having information about you that is too incomplete or too inaccurate can really fuck up their shit.

2. In domains where customers are extremely profitable (again, e.g. insurance and financial services), it can likewise be extremely expensive to acquire the data needed for robust modeling, even dirty data.

In both of these cases, they do very much care "about having data about 'you' in particular".

> You yourself are only a tiny and statistically irrelevant piece.

Perhaps, but they engage in so much effort to spy on me and defeat my protection against them that this distinction doesn't actually matter.

Right up until the exact moment you aren't.

At the moment, from various advertising agency surveys, it seems that small/local businesses are still "dipping their toes" into digital ads and not really trying to track their audience at all beyond simple geographic segmentation.

The bigger agencies are building their own databases, but they haven't been able to link ad spend and customer purchases effectively, so that's the main focus at present. In particular they need to know ROI to effectively budget ad spend. Obviously, they have estimates of these numbers, but not an accurate per-ad-buy prediction. Google/Facebook are full of clickbots and there seems to be minimal incentive on their part to remove the bots. They've made some efforts with pay-per-conversion but it seems like marketing theater rather than a business model shift.

So until the fraud problem is solved, I don't think they care about microtargeting too much, except for its anti-fraud properties (attractive ad profiles are hard to fake).

Not every conversational point in an online forum needs a formal citation.

They would if it were free, but getting the marginal information isn’t that valuable for them while being relatively expensive

I am pretty sure they are not interested in you per se, but at all those people like you.