If spacetime is curved by object with mass, just like the sun curves space time and so makes the planets orbit around it and will eventually in time make them crash towards it then shouldn't the entire universe be warped by the most massive object within it and thus make all objects circle around it and eventually attract all object towards it? Therefore shouldn't the universe be contracting rather than expanding?
One answer to your question is already written by you: eventually. An envisaged final state of a system may not be informative about its current state. But there are two more simple arguments.
- Even the most massive object does not have an infinite escape velocity, so objects kept together only by gravitation may never turn back towards each other (or even orbit around each other).
- It is not the Newtonian gravitation but general relativity theory (containing some important unknown factors, like dark matter, dark energy) that drives the evolution of the universe, so IMO not many cosmologists would dare to bet on what is going to be its fate in the long run.
At large (cosmological) scales, the mass/energy distribution in the universe is extremely uniform. In other words there aren't any heavy "central" objects that would attract the rest of the mass.