Louis Walsh is widely known as gay - it's just not really talked about. As already mentioned, it apparently to protect his mother. He was fairly well known on the scene in Dublin. In 2011 he was accused of sexual assault by another man which threw him into the papers in an unflattering light, though it was proven to be untrue and the accuser admitted he lied.
On Amal Clooney, I think she craved the lifestyle that comes with celebrity rather than the money. It's the connections - Clooney is friendly with Brad Pitt, Leonardo di Caprio, a load of famous movers and shakers. I don't think there's anything genuine about their connection. If it works for them, so be it, though bringing kids into that sort of dynamic is pretty complicated.