I can tell you that with our most powerfull telescopes we can find no 'end'. If I look over the side of a boat into the ocean I can't see its bottom. This doesn't argue that the ocean is bottomless. It only argues for the limitation of my range of sight. You're merely assuming there is no end, and then arguing that your assumption is true.
Observation shows that the universe is expanding.
The more rational conclusion is that it is a collection of finite properties because that is what we observe. Not every idea is something that could actually be the case. ES All we know is what we observe, which is expansion of the finite. Infinitude is a hard thing to grasp. It only takes normal observation to substantiate my claim.