Yeah, but the faster speed of light through vacuum can still be enough to make up for the longer path.
Back-of-the-envelope calculation: at an altitude of 550km and minimum elevation of 25 degrees above the horizon, a single Starlink hop could cover a maximum of 1880km of distance along the earth's surface, with a ground-satellite-ground length of 2068km.
So the total distance traveled through space is about 10% farther, but the signal goes 50% faster than through fiber, which is enough to cut your round-trip time from about 19ms to 14ms (plus any extra latency introduced by routers). That's nothing to sneeze at.
The 3rd parent was suggesting hollow core fiber, which I _think_ is supposed to reduce the distance travelled to near fiber length through band gap effects i.e eliminating the extra distance travelled in regular fiber core due to total internal reflection, hence the lower latency. Light still travels about 2/3 the speed in silica core compared to in a vacuum, so it would make the fastest possible speed 2*10^8 m/s (per meter of actual fiber)
So in order for LEO satellites to compete, the total distance from A to B must be less than 1.5 times the equivalent of hollow core fiber on the ground.
Oh god I have to do trig! So finding the ratio of the the horizontal (ground) to vertical (altitude) when the hypotenuse is 1.5 * the horizontal =
(1.5**2-1)**0.5 = 1.118033988749895.
i.e 1:1.11 half-ground:altitude
550 / 1.118033988749895 * 2 = 984km
i.e A single hop Satellite at 550km altitude would beat a straight line (ignoring curvature, bored through the ground) hollow core fiber at 984km (I _think_ :P). Realistically you can probably lower the distance since we don't actually get straight line A-B fiber, but that's still quite a long minimum distance.
Disclaimer: there are too many assumptions and approximations in here, it's just for fun.
[edit]
whoops, hollow core is supposed to be almost speed of light, so actually it's not much of a competition any more in the idealised case.
Back-of-the-envelope calculation: at an altitude of 550km and minimum elevation of 25 degrees above the horizon, a single Starlink hop could cover a maximum of 1880km of distance along the earth's surface, with a ground-satellite-ground length of 2068km.
So the total distance traveled through space is about 10% farther, but the signal goes 50% faster than through fiber, which is enough to cut your round-trip time from about 19ms to 14ms (plus any extra latency introduced by routers). That's nothing to sneeze at.