I don't think that loud, high pitched tinnitus is
necessarily a bar to habituation. For instance, I read this on reddit just yesterday:
https://www.reddit.com/r/tinnitus/comments/3fvmtl/my_experience_of_overcoming_tinnitus/
It seems to me that some brains just seem to flip a switch at some point and find a completely different way to relate to the perceptual input -- and while oftentimes people report some kind of conscious effort finally leading to a breakthrough in this (as in the link I just posted), it's not correct to say that you can consciously
force that to happen, it seems to be a time process.
It's worth remembering that every nerve in your body is
constantly firing and providing perceptual input to the brain, the vast, vast majority of which is discarded before it ever becomes a conscious percept. For instance, my feet are uncomfortably cold right now, and on some level I've been aware of that all morning but it's not really "bothering" me.
Bothersome tinnitus requires a couple different glitches: first you need an audio processing problem which generates the sound in the first place, but this only causes the perception, and not the conscious thought / distress. For that, you need a glitch in the filtering which is constantly scanning percept streams at a subconscious level and discarding 99.99% of what's there.
If your brain was not still capable of filtering out a ton of garbage and noise, it would not just be tinnitus overwhelming you: the slightest change in perception, like a gentle breeze running through the room, would seem like an unbelievable overstimulation, impossible to endure. (There are people with very, very severe sensory processing issues who experience the world like that -- for instance, some people with severe autism report an inability to chuck-process visual data, so where you or I would see a boring field of grass, they see a billion individual blades of grass and find it overwhelming and distressing).
For me the bottom line is that even though my tinnitus annoys me, overall, my sensory filters work pretty damn well, and therefore the optimistic and reasonable thing to do is to assume that my brain will continue to filter the T percept better and better over time.
Of course you can find horror stories of people who just get worse and worse, but
so fucking what? You can find horror stories of all kinds. It's entirely possible that in fifteen minutes your body will develop a horrid crisis which will make tinnitus seem small in comparison: you could randomly have a stroke that leaves you completely unable to communicate, or you could develop CRPS and spend the rest of your life in unbelievable physical agony, or you could get struck by lightening and become so severely brain damaged that you don't know who you are. What's the point in even thinking about such things? One day or another, you're going to develop a crippling health issue, and spending your whole life in fear of that isn't going to change it. In the bleak, Sylvia Plath view, we're all broken and hopeless. Do you find that comfortable? If not, then just reject it: we all create our own reality, in every minute of every day.