People love free but they really hate obnoxious ads.
There are plenty of services that once had “no ads” as a selling point, but later added them. I suspect this is partly because the act of paying not to see ads demonstrates that you have a certain level of cash and willingness to spend it, which makes you an attractive ad target, which raises the bids of the ad agencies. I’m not saying this force is impossible to overcome, just that it may be stronger than you expect.
There are plenty of services that once had “no ads” as a selling point, but later added them. I suspect this is partly because the act of paying not to see ads demonstrates that you have a certain level of cash and willingness to spend it, which makes you an attractive ad target, which raises the bids of the ad agencies. I’m not saying this force is impossible to overcome, just that it may be stronger than you expect.