What is wrong with always staying legally single, never marrying or having kids, and just date to have temporary companionship and sex?

Hi all. In this day and age, I think marriage is outdated and unnecessary. People get married and divorced all the time and then you gotta pay alimony and child support for many years. I'm almost 40, never been married, don't have any kids and I think the way to go these days is to just date occasionally, enjoy female companionship, have as much sex as you can during that time and then eventually break up and move on. To me, that's the smart way to deal with dating in the world today. It's very clear that nature doesn't want the same man and woman staying with each other all their lives but to change partners from time to time. Statistically speaking, people will eventually leave you anyway for all kinds of different reasons. This is why I think marriage is a dumb, outdated idea in today's world and it should be abolished. What do you think about that? Thanks.