Kind of a weird question I guess...but please bare with me

I've seen guys at the gym where the barely-a-tank-tops and my guess is that it's for comfort, less in the way during upper body workouts (Correct me if I'm wrong). Then I see guys where sweatshirts, with their hoods covering them, sweating profusely. All I could gather would be that they are doing this on purpose for some reason and I don't know why? Some guys go the extra mile and wear a baseball cap under all that.

The other day I tried the sweatshirt with hoodie. I have to say, I felt great. I was drinking WAY more water/electrolyte/BCAA drink to stay well hydrated but at the end I felt better. Perhaps a placebo effect? By sweating more am I doing something good/bad?

Also, with the hoodie up, it actually felt like I was all alone...I don't know if that's the reason others do it, but it had me more focused.

So, is a good sweat always better? Or is it doing something I don't know and should know? I also found, especially now with this cold as f**k winter that the slightest breeze that comes into the gym because somebody has decided it's hot and opens a window for a second, makes me feel a bit sick/dizzy.

Any science to this? Or is it way more simple than I'm making it out to be?