If you'll loose people who are - maybe - important for some questions, like metrology, then it is again Dave's decision to do so.
As said, if i see the forum is full with such unwanted advertisement, and I'm not going to get rid of that, I'm fully out of the club here.
I'm quite puzzled as to the reaction here.
I have added just one extra ad to the bottom of the forum, albeit a sticky one.
But for 15 years hardly anyone has complained about the large ads at the top of the page you have to scroll past
every time just to get to the content (and they are still there as I type this in the reply box).
I find these vastly more
annoying than the bottom sticky.
I expected some push back for the bottom sticky, I get it, it's different to the other ads that just scroll with the page, I get when people say it's annoying, that's why I thought I'd trial it and see what reaction it gets. But I'm genuinely puzzled as to why it's suddenly some massive red line for some people

What if I said the bottom sticky (or a side sticky) could replace those large ones at the top, would people say it's still going "too far"?
Dr Frank, am I reading you right in that you would rather leave the forum entirely over that bottom sticky, instead of just installing an ad blocker?
I have no doubt there will be a few people who will leave the forum over something like this, there always is people leaving for whatever reason, that's just human nature I guess.
If I added a paid feature where you could pay to remove the ads then I'm sure there would a few people for who that is a red line.