I care about basketball, not about API costs and I don't find mod's job that much useful for aggregating daily threads on results and most recent NBA relevant tweets.

If basketball discussion is what you care about, then who cares if the discussion takes place on Reddit? Forums are a dime a dozen.

so you care about having a place to gather, to talk about your hobby and usually at the mods' effort to aggregate content (I assume since these are always the most upvoted and most commented threads on match day), but you don't find their job "that much useful"?

"I care about getting my $2 T-shirts, not about whether Walmart's employees can afford to pay for rent, food, and heat in the same week without relying on public assistance!"

Just because you don't appreciate the work that other human beings do doesn't mean that they deserve to be treated like shit, nor does it mean that when they stand up against greedy bastards who care neither about them, you, nor the product or service they're selling you should throw them to the wolves just because it inconveniences your life.

Reddit modding is a hobby, not a job you do to feed yourself, stop with drawing ridiculous strawmans.

what percentage of reddit users use apollo or another 3rd party app?

Depending on which post you look at somewhere between 1% - 6%. But, the more important question is which users use Apollo (or other 3rd party tools).

The answer overwhelmingly is mods and content creators, the most important people to Reddit's success.