do you ever get "tolerance" to CPAP?

Good point, if there were a down side to more air/oxygen than normal,
jazz trumpet players, glass blowers, and hog callers would be dropping like flies.

Your body adapts to apnea. You manage to sleep despite being strangled. Your body adapts somewhat to low blood O2, stress hormones, bad sleep, etc. There have even been some studies showing apnea causes your body to generate more "alternate" blood vessels in adaption to the low O2.

If you use CPAP for a while and then quite, the apnea will probably bother you more than it did before CPAP, at least for a while. You'll probably sleep a lot worse. You might even be more prone to things like heart attack or stroke until you readjust to apnea.

I feel confident the reduction in risk from using CPAP far outweighs the short term extra risk if you stop CPAP.

As to some sort of damage to your body from CPAP, making your apnea worse, I've heard no information indicating that actually happens.

I googled this very problem and found this post. I started CPAP four years ago with the pressure of 9. It worked well, at least for a little while. I did another sleep study a few months later because I was having too many events again, and the doctor increased the pressure to 12. Another few months later and another sleep study because of returning events at a very high-level, and the pressure went up to 15. Fast forward to couple months ago the last Sleep Study recommended a bi-level APAP and the pressure set to automatically go up to as much as 25! And tonight I feel like I can’t get enough air; I stop breathing so many times that it wakes me up within a few minutes of falling asleep. The pressure is so incredibly strong that I could aim the hose at the wall and it makes the curtains move dramatically.

So, I am very concerned that before the CPAP my body would fight to restart the breathing but had established some sort of equilibrium. My very first Sleep Study indicated perfectly fine oxygen levels even with the severe apnea events I was having. And now my body seems to have sent away its guards, so to speak, and says to the machine, hey since you’re here you can do the work for me.

However, based on all the replies I’ve read, it appears my situation is somewhat unique. I hope I’m wrong, and I hope most of these people replying to the main post are right, and that this slippery slope is not happening but rather a solution is coming

You very likely needed the higher pressure all along.
The doctor was either following antiquated protocols or fumbling around in the dark.
Eventually, even a blind squirrel finds a nut.
When we enter this forum, lights come on, and we can see our way.
Some of us do it before our medical team gets a chance to fail us--if we're lucky.

I started at 11 and was raised to 13 a few months later. That was almost twenty years ago (yes, 1999). Now I'm at 13½, so really, I have not had a major escalation in my pressure. Unless you're near the capacity of the machine, or put on a tremendous amount of weight, you don't need to worry about this.

All CPAPs on the market today can go up to 20 (and down to 4) in increments of one or finer (most at least in increments of ½).