In my opinion the way to think about SuperHeavy+Starship is a scaled up stainless steel Falcon 9. Currently Falcon 9's first stage booster (usually) lands and is quickly/cheaply refurbished/reused, while the second stage is completely thrown away except for partially successful attempts at fairing recovery. They've used this partially reusable system to do a large number of launches quite cost effectively.

In SH+SS, the "Starship" part is the second stage, with the revolutionary goal that it can deliver a payload to orbit and then skydive back to earth and propulsively land itself. That has major risks and is unlikely to succeed the first number of attempts, with the loss of the stage and the 6 raptor engines.

The "Superheavy" portion is very much equivalent to a scaled-up F9 booster, and the risks to landing it should be much lower (Elon's crazy catch ideas notwithstanding).

tl;dr I think Starship system can mostly work if it's partially reusable to a similar extent as F9. Losing a half-dozen second stages to do a full orbital refueling for a Moon or Mars mission should still be a fraction of the cost of a single SLS launch, and they can continue working on full reusability while performing missions and cashing checks.