I believe they can still commit highway robbery even without their net margins being dramatically high, since highway robbery is exactly what you stated - charging too high a price for its products/services.
For high-bandwidth large-terminal, you have Inmarsat GX, Viasat and various other Ka and Ku band based providers; for safety of life you have Inmarsat and Iridium (except at the poles, where it's Iridium and HF); for land-based tracking, you have Globalstar and Iridium; for handheld telephony, you have Iridium, Inmarsat and Globalstar.
Notably, Starlink also does not look like it will be competing in any of these fields.
a note that part of the DoD iridium market where Iridium was previously the only ultra-high-latitude/polar coverage part is served by the DoD's own molniya orbit satellites which provide full polar coverage. the orbits of these are designed to be at apogee and long dwell time directly above high latitudes.
the DoD is still a big part of iridium's revenue stream in general of course.
If anything, it seems like the customers should feel lucky the investors are risking their money on this product/service, and it is being offered at all.