I don't think this applies to everyone, but specifically the young guys maybe in high school/college/early career who haven't really had experience with girls. It's supposed to be awkward, its supposed to be hard, when its too easy it fucks you up.

Theory

For young guys, prostitution has a cost beyond the cash you pay for it. When you pay a women for sex, somewhere you're teaching yourself that you're not worthy of sex and need to pay for it to have it. Not only that, but getting it on demand and so easily spoils you and trains your brain to think that you shouldn't have to put in effort for it or improve yourself for it. Trying to talk up a girl becomes impossible and tiresome.

This is really fucked because sexual drives are one of the most instinctive human drives. There are even some theories that suggest that all human creation from skyscrapers to space exploration is the manifestation of delayed sexual gratification. Essentially, your sex drive is often tied to your drive to achieve things in life.

Anecdotes

I personally know of guys like this, that pay for sex early and get spoiled by that and keep doing it. One of these guys was 6'4'' big dude who went to the gym with us every morning. He lived one door down from me in the biggest room of the frat house and in my two years living there he did not have sex with one girl. This is despite literally hundreds of girls coming to our house every Friday and Saturday looking to get fucked by a frat boy. Yet he bragged constantly about how many girls he would fuck every summer from paid whores or how he got a blowjobs without paying for it and scamming the prostitute.

I used to be friends with a few of these guys but cut them all off. Every single one of them is really negative and kind of a loser not doing much with their life. None of them has lost their virginity with a real girl and is completely unable to meet girls, talk to girls or get into a relationship. People don't talk about that drawback of prostitution.

Devil's Advocate

I think if you're older and have had experience getting girls and just want to have sex it might be okay. Or resigned to the fact that you can't meet someone (like you're disfigured/disabled/super old/etc.) I can see how prostitution makes sense. My mentor makes millions of dollars per year and exclusively fucks high class escorts he pays upwards of $10K for. He tells me that relationships take too much time he could better use making more money but I'm not sure if that's the real reason. But either way, it definitely doesn't stop you from being successful if you're mature enough for them.