IANAL, but...

>a) I block or skip ads in media I consume

>b) 1000 people block or skip ads in media they consume

Not doing something is generally considered okay, even if it decreases someone else's revenue. eg. saying that a given product is a scam and not worth the money (assuming it's true). Same with skipping ads (eg. TiVo)

>c) I convince 1000 humans to play my songs every day and all of them listen to the ads

>d) I convince 1000 of humans to play my songs every day and all of them skip the ads

Legal, because the whole point of advertising is to convince people to do something, even if it costs someone else money (eg. drugs, which might cost your insurance provider money). Where you might get into trouble is if the actions turn out to be fraud, eg. telling people to stream music, even though no one's listening to it, for the sole purpose of getting streaming minutes, or setting up a kickback scheme (might be tortious interference). Again, going back to the drug example, it's pretty intuitive. Advertising a drug? That's fine. Telling people to buy your drug, just so they can chuck it into the trash, for the sole purpose of enriching yourself? Probably illegal.