Agreed, bad posture (not just neck but in general) can cause both tinnitus and RSI-like symptoms in my experience and I have been able to tackle both with proper exercising.

Where I don't agree is the following:

> Turns out the process to straighten your neck - even after like three decades - with just some casual invest everyday only takes about a month or two.

While you can make progress quickly (in the sense that your symptoms become less severe), fixing your posture usually takes much, much longer than that. In fact, if we're being honest here, it's never a one-time fix that you do for some $TIME and then stop doing. The reason being that forces & activities that cause or exacerbate bad posture (sitting, carrying a back pack, sleeping on the side, various sports, doing no sport at all, wearing shoes with a high heel drop, …) are not a one-time thing, either. They act continuously, and so "fixing your posture" must be a continuous life-long activity, too.