"Three tracksuit wearing yobs with knives" ?? I don't know what "sexual encounters" you're into personally
I don't know what's difficult to understand about this. I'm not saying that the sexual encounter per se is violent; I'm saying that the prospect of sex, all too often, is used to lure men into dangerous situations. We don't know whether the prospect of sex is legitimate or not because we do not have psychic powers.
You can meet a nice woman online, but the profile may be fake and it may be a man behind the profile picture, luring you into a trap. You could meet a nice woman at the bar, but again, she could be working with a gang who will attack you.
but this really is not a big risk for men in general.
It's unusual, but it happens frequently enough for it to be a concern.
There are precautions I take when meeting someone new. For example, if I met a woman on a dating website, I would only meet her in a public place, and I would tell someone else where I am. When I went to meet a friend overseas who I had been talking to online for years, I told someone else exactly where I was going and to check up on me to make sure I was OK... in this case, I was meeting a man and it was just for friendship so it wasn't sex related, but I would have taken the exact same precautions if it had been a woman. In another case, I was going to meet a woman for sex, but declined because I knew nothing about her and there was no air of legitimacy around her online profile, so it could have been anyone when I walked into her apartment... a gang of yobs, who knows.
I don't know why this myth persists that all men are 6'5'' muscle men who are never attacked because everyone is afraid of them. All people are at risk of violence, and it's important we all be careful. My mum always told me to be careful when going out, when meeting new people, etc... wise words.