Sure, question away, but if people are supposed to agree with you, you kind of need to supply some data or evidence. Skepticism is more than just saying "nothing is really known for sure" or "people have been wrong before." That argument won't overturn the prosecution's case in a court of law for example. What they test for in court, and in science, is reasonable doubt. Give them a
reason to doubt, and absolutely they should doubt. People should reconsider their opinions when presented with contrary data. The problem is that you're not presenting any data. The people you're arguing against, have presented data.
At their peak in 1989 before the Montreal Protocol went into effect (and a strangely coincidental multi-year observed trend began of rising ozone concentrations over Antarctica), CFCs were at a concentration of about 2 parts per billion. 70 years of humans releasing them worldwide could absolutely produce that, especially when you consider the long lifespan of those molecules. And they're a catalyst for the ozone breakdown reaction, not one of the reagents; so like most catalysts, they don't get used up, and like most catalysts, there is very little required in the first place.
The classroom experiment might be leading you to overestimate how much CFC output would be required. Probably because the threshold concentration required for half of people to detect a smell -- let's say of ammonia, like after cleaning something with it, or in your cat's litter box, or near a place where people have been pissing -- has to be about 5 parts per million or 2,500 times as much as the peak CFC concentration in 1989. For ethyl alcohol, that cops seem able to smell like bloodhounds when they pull you over, the odor detection threshold is about twice that, or 5,000 times the peak CFC concentration. On the other hand you can smell hydrogen sulfide at only about 20% of the CFC amount, so hey. Maybe it's not a relevant experiment? Except to illustrate the concept of diffusion, which I already addressed satisfactorily, but now your concerns have shifted like a moving target to something else.
How quickly an answer was found in 1985 has nothing to do with that answer's veracity. If a mosquito bites me in the ass, I figure it out right away; that doesn't mean there's no mosquito on my ass. How long an answer remains the accepted answer has nothing to do with its veracity either, which I think is what you're pointing out, but that also cuts both ways; its longevity doesn't falsify it, for example. If I'm right-handed for 40 years do I start to doubt my "handedness" because it didn't change often enough over the years? Because it's suspiciously consistent?? If anything the opposite happens, and it's the same in the science world: There are many professional, honest and earnest people out there making measurements and reporting the results. And if someone made a discovery that could overturn the prevailing ozone depletion theory, there is every incentive both professional and otherwise, to do so. That person only has to publish their data.