Those secondary effects are all part of the first point: "lose money".
I'd say it's the opposite: the first scenario (ground the aircraft type) would suffer less from those secondary effects. Once all the airlines on your region are no longer flying that aircraft type, people no longer worry about whether they're flying on a MAX8 or a non-MAX8; they know they're flying on the "safe ones", so they have less reason to memorize the name, to check the aircraft type on their tickets, to tell their loved ones "avoid that airplane", etc.
The third scenario is the worst case, if there's a third accident with the same cause (or at least perceived to have the same cause), the reputation of the 737-MAX8 will get tainted, and that taint could even spill to other 737 variants (less knowledgeable people don't know or care about the many variants of the 737, to them "737" is the airplane type).
- Ground them for nothing and lose money
- Not ground them to save money, no crash happens before the cause is found and a fix is deployed
- Not ground them to save money, and see a third crash happen, killing 150 again
And that also doesn't consider secondary effects, like the loss of confidence from the public on that aircraft type, or the potential confusion from the public between 737-MAX8 and 737-800.