This is exactly why you shouldn't do a math masters.
Listen, if you go to MSU or Vandy and are obviously a star, it's possible the faculty would support you in reapplying to higher ranked places. In that case, you'd have taken the core sequence at a very good program and have a chance to move up. Three cycles ago, Sammy6 on this board applied as a transfer student from a school in the MSU/Vandy range and ended up at Harvard. I know another guy who went to UIUC(albeit some time ago). After spending a year there, his advisor thought he should move up, and he ended up at Stanford. These things are possible and can happen.
On the flip side, if you're not top 5 material, you'll figure that out, and you'll be better off for having gone this year rather than putting it off a year. Putting it off seems an unnecessary risk for a large opportunity cost.