Savers are useless non-contributors. Not that there's anything wrong with saving, but economies of scale don't depend on it, and so there's no economic justification to encourage it.
You cannot be more wrong. Saving is simply deferred spending. It's spending later vs. spending now. You could argue that incentivizing spending over saving is transferring prosperity from the future to the present. In the end it's a zero sum.
Don't be ridiculous. If the economy were to collapse tomorrow all your "deferred spending" and "future prosperity" did nothing to help it. Trade volume is always low when saving is incentivized, and won't increase in the future because people decide to suddenly stop saving en masse.