There are lots of reasons why people lean toward the conservative or liberal side of social and political issues. There's little doubt that among them are intellectual considerations, but I suspect that one's temperament, the nature of one's religious commitment, and one's experience in life also play prominent roles in whether one tends to list toward starboard or port.
Be that as it may, these factors don't explain everything. A long time ago I read an essay that argued that there's another, more urgent, reason which accounts for why a lot of young men at least profess to be liberal and that is that they're profoundly interested in girls. I can't recall much about the essay except the general gist of it. It went something like this:
It is, from the perspective of some young men, an unfortunate fact of life that conservative girls often believe it is their duty to preserve their chastity until they are married. A young man, interested in exploring and exploiting a young lady's charms, could invest a great deal of time and treasure in such a girl only to have his investment come to naught. Thus conservatism has limited appeal for many men under a certain age.
Liberal girls, contrarily, are often convinced that such rules are remnants of an oppressive male patriarchy that must be rejected root and branch, and that they have an obligation to stand in solidarity with the sisterhood by liberating themselves through free expression of their sexuality. This, of course, is precisely the attitude that makes the eyes of oppressive males light up. They couldn't agree more. They, too, support a woman's quest to liberate herself from the shackles of puritanical prudery and male subjugation. The sooner she consummates her liberation the better, and he wants her to know that he will always be there for her to help her in any way he can to accomplish her emancipation.
Moreover, if a conservative girl gets pregnant she often feels it is her moral duty to bear and raise the child. This is a horrifying prospect for many a young man. Liberal girls, however, believe themselves to be sovereign over their bodies and that it is some sort of sin to let a baby ruin her life. This conviction is sweet music to the ears of said oppressive young men who dread the idea of child support or, worse, marriage. By all means, a woman should have the right, even the duty, to abort her child. Why should she, and by extension he, be tied to an unwanted child for the rest of their lives?
Thus it is in the interest of many young males, as they see it, to reinforce liberal beliefs about sexuality and abortion among their female friends and in society at large. To be credible, of course, they also have to adopt liberal poses on other issues as well, and so they do, not out of any principle, except perhaps the principle of pragmatic expediency: Whatever works is right.
So, for at least some young men, and you know who you are, their liberalism is simply a means to an end.
RLC