It's obviously enormously difficult to estimate figures on this, but from rough observations and calculations I've got a (very rough) figure of 1 in 20 men, or 5%, who have sexually assaulted.
That's higher than it ought to be but it's considerably less than 30%.
The gap between the two is consequences. Which is why the level of rape and sexual assault jumps massively during war, genocide, in very poor countries, any time when men are relatively rich and powerful. Places where the fear of consequence reduces, the rate of rape goes up massively.
And the obvious point is that when, as in the UK, consequences start to reduce to zero because of rape culture and a lack of conviction, well it's not rocket science is it?