I think it's probably more men than women just because it's socially acceptable and even encouraged for men to be like this whereas it's socially discouraged or seen as immoral for women to do this. I know it's changing now but it's still the case I think.
I think that the societal expectations ARE the problem actually. There's nothing wrong with wanting casual sex, but there's also nothing wrong with wanting sex to be in a relationship, it's just personal preference.
The problem comes when a man who wants casual sex believes that all men want casual sex and all women want relationships. Therefore he believes that to get casual sex he must pretend to want a relationship. He perhaps even believes that all men who are in relationships are just playing along for the "bonus" of regular sex.
Likewise, it's a problem when a woman who wants a relationship believes that all women want relationships but all men want casual sex. Hence, she ends up playing ridiculous games and doing things to try and trick the bloke into a relationship and is a bit suspicious of someone who genuinely does want a relationship.
Then you get awful "dating guides" like "the rules" and concepts of boaktastic pick up lines, and people doing all sorts of ridiculous stuff and behaving in ways they think they should rather than how they want, in order to extract this seemingly impossible thing from the opposite sex.
It would be easier if people just realised that some men want relationships, some men want casual sex, some women want relationships, some women want casual sex, could be open and honest about their intentions and end up with someone who wants the same thing as them. No heartbreak, no lying, no mind games, no "rules" because men and women aren't some cookie cutter same thing.