Maybe some do, but I've never needed it. Often I actually find public speaking easier than small groups. In a small group my brain is trying to "model" what each person is thinking about my talk, as the groups get larger that becomes impossible and I tend to relax and let go. I also find the energy in a larger setting is a useful feedback mechanism. I might toss a small joke out and see if the audience is engaged, or I will ask a question and get a show of hands. The more I engage the calmer I feel and the more enjoyable the experience is for me and my audience.

Exercise increases heart rate. The more we exercise, the more the heart gets used to that adrenergic stimulation. This decreases the number of receptors to sense adrenaline in the heart, so whenever adrenaline rises again into the system, like in public speaking, we can handle it much better.

Exercise mitigates public-speaking anxiety. Particularly prolonged cardio.

But what a godsend propranolol has been for a contentious work situation causing extreme anxiety.

Wonderful to take ahead of a scheduled meeting that could have otherwise been an hour of physical panic that no rational thought (this will feel unimportant in a week, it's just job, etc etc) could quell.

Eventually, your body learns to adapt and understand that this thing you dreaded isn't so bad after all