You are never as physically or emotionally vulnerable as when you are naked and having sex. To do this carelessly is quite strange. Yes, we all have sexual urges and would like to be having a lot of sex with a lot of different people, but actually doing that comes with big costs.
Being in a physically and emotionally vulnerable state, having sex with someone, do you think you will forget that? If you don't, why do you think they will? How can you know what it meant to that random person? How might they try to get involved in your life in the future because your "one night stand" or "just sex" meant more to them than it did to you?
Theoretically let's say you are an absolute chad running around slaying pussy by the truckload. Do you think none of these women are going to try to get knocked up simply based on your good looks and either hopes for commitment or not even caring about the commitment if it means they can have an attractive kid? Sure, plenty of women focus on their career over everything else and will get an abortion, but there are also plenty of women that dream of having an attractive kid, and if they can sleep with a really attractive guy they don't care if he will stay around. But wait, when they realize if they try to get child support that means you will have to continue to interact with them, and maybe you will come around and have sex with them again at some point, even if they don't care about child support they probably will pursue it eventually if you were worth banging in the first place.
People who imagine consequence free sex haven't really thought about it. It's an interesting concept, but it just doesn't exist in real life. If people want to have sex with you, some of them want to have babies, and then there is the emotional aspect of it. If you can get that physically close to people and it means nothing to you, I can't imagine you are mentally healthy and stable.
My grandfather was what a lot of people would consider a chad who impregnated dozens of women, some of them multiple times. The aftermath is,
1: He was shot twice in the back by different women that he had led to believe he was in an exclusive relationship with. In both cases if the bullet was in a slightly different place he would have died 30-40 years ago and wouldn't have done half the things he has since done in his life.
2: He pays child support to a large number of women. He will not say how many. He does have a large income so he can afford to do this. He has mostly tried to avoid going to court and just agrees to pay them a set amount every month outside the court system but this doesn't always work out.
3: He has dozens of kids who are really pre-occupied with their weird childhoods where they did not have a dad. I have a huge extended family and many of these families do not like each other because their mom was not the one he married. I am related to a large number of people with alcohol or other substance abuse issues, and of my aunts and uncles there are very few that do not have serious issues, and despite them now being in their fifties or sixties, they are still obsessed over stuff that happened when they were kids/teenagers, much of it related to family life.
4: There are a large number of scorned women and other people that hate my grandpa's guts. He would have impregnated far fewer women if he was honest to them about what he was doing. These days things might be different because people are less concerned about marriage, but back in my grandfather's day, if he was just honest about his intentions and what he would or would not do, there are a lot of women he would not have impregnated, and may have gone on to live much happier lives. I'm imagining this kind of thing still happens somewhat frequently.