It is no single thing, but rather the number of adjustments that have been required. Note that I am a non-specialist in cosmology and I am relying to a considerable extent for a proven talent at smelling out bullshit. I have no viable alternative. That is why you will find examples on this and other forums of me attacking anti-Big Bang posters for the weakness of their arguments and where I will espouse a standard Big Bang viewpoint. It's not just the best game in town, it seems to be the only game in town. But I don't have to like it. Philosophically inelegant? Something undefined 'winds up' something undefined by some undefinable process then everything runs down over billions and billions of years. A Universe that can reflect on itself, as this one now can, should be capable of more.