Stuff like this is an outlier but I've also seen this behavior at the gym. This is from like 2 to 3 years ago, there was a regular that would approach literally every attractive woman there. I've spoken to him before and he is a nice guy but he never showed any signs of respecting boundaries and was way too pushy. I remember this one particular time he approached this girl, I'm not sure if he had spoken to her before or not and it suggested they might have. Anyway, he was talking to her and she said "I can't hear you right now, I have my headphones in" and instead of backing off he just kept persisting. I remember a few weeks later seeing him try again with the same girl whilst she was in the middle of doing shoulder raises and she obviously ignored him and walked off when she was done. It was super cringey to watch and as you said it's men like that which ruin it for guys that are more normal I guess you could say.I've seen a few guys get banned from the local gym for being creeps, they ruin it for the rest of us.
Op just go there to workout, once you get a good body and confidence go outside and approach women.
I also remember another time when this same guy was talking to this woman there and he tried to hug her and she said something like "We can't hug, I barely even know you" lol.