It's not the majority, but it's absolutely not uncommon.
For me it's like left handedness. Not the norm, but you'd hardly be shocked to discover someone was!
My XH was a habitual prostitute user. You'd all like him. Not an alpha male, but no loser. High earning but from family business - so don't assume that shows drive and ambition! Stupid when drunk but not really laddish. The first to pitch in with washing up when on a group holiday, happy to lend a hand with a house move. Not Brad Pitt, but far from ugly. As a sex worker above said - he was your average Joe.
The 20-30% figure doesn't surprise me.
OP, your husband isn't even pretending to be sorry. He's telling you to shut up it's no big deal. And he's lying to you - really, the chances that you caught him the one and only time and anyway he didn't go through with it? BULL SHIT.
Add to that his and your faith? How can he possibly say you're over reacting when it's against your faith?
He doesn't give a shit and he'll carry on using prostitutes. Surely his attitude tells you that? I'm sorry, I know that's blunt.
As for all the talk about how many do it, what types of men, why, whether sex workers are consenting or immoral, whether it's OK to pay for sex or grim, or whatever... interesting but irrelevant
When you marry someone you agree that you are in an exclusive relationship. Small % exception who agree they are not - but this is a norm we can all agree on. The norm is that when you marry someone they don't go and fuck someone else!
So OP, forget how many men do this, forget wondering why some women will take their money... and accept that your husband has fundamentally betrayed you.
And get rid, before you live a half life of a shitty marriage to a man who doesn't value you or your shared faith.