The main threat mentioned here is governments sabotaging cables in order to disrupt Internet connectivity, but another important one (that's deliberately invisible) is governments tapping these cables.
Even though we have a lot more transport encryption nowadays, communications metadata is still very vulnerable, and undersea cables are appealing targets to spies.
If you click on the segment, can see that it is Tampnet. It looks like they provide fiber and mobile networks to offshore drilling. That is right location for oil fields.
Like your fun, but for some extra seriousness, 10k$ is the order of magnitude you pay to setup FTTH in a big city. Most times, consumer ISPs eat the cost and make economies of scale by connecting entire neighborhoods, but if you don't have that chance and for some reasons ISPs won't connect you you can count on 10-50k$ infrastructure bill.
Also, consumer ISPs like Comcast are the worst. If you have good relationships in your neighborhood/municipality, going collective like with SCANI/Freifunk is always going to be more interesting and useful.
Even if we were superhumanly competent at on-land infra, you still have to negotiate right of way and bury hundreds of miles of cable overland. The ocean way they just drop the cable off of the back of a boat.
How things have changed since FLAG (https://www.wired.com/1996/12/ffglass) which instead of being owned by hyperscalers for their never ending desire to monopolize all the things, was owned by telcos looking to open new markets in Africa.
Seems like Starlink has potential to completely disrupt undersea cables once the network is larger. Obviously it wont ever be the same latency or bandwidth as an undersea cable but it would be near impossible to tap and much cheaper.
You might need a drone with an antenna the same size as the ground station's. I haven't seen the ground stations, but that might be hard to put on a drone.
You're right that it won't be the same - it has the potential to be faster.
Speed of light in a vacuum is higher than what can be achieved in a fiber-optic. Combine that with a more direct path than what can be achieved with an undersea cable and things start to get interesting.
Even though we have a lot more transport encryption nowadays, communications metadata is still very vulnerable, and undersea cables are appealing targets to spies.