Every country but the US has had very bad luck with Mars landings. Its a non-trivial problem to solve and even the US's expertise and funding leads to failure sometimes.

https://en.wikipedia.org/wiki/List_of_missions_to_Mars

The idea that there's a conspiracy at work is ridiculous. We're not exactly at the "Star Trek" stage of humanity here. Landing on Mars is still risky.

I agree it's very unlikely that sabotage is what's going on, but what you're saying is the one compelling argument in favor of sabotage. "Everyone but that one actor has very bad luck" is exactly what sabotage looks like.

Except that actor has the most advanced space program in history. Its like saying Michael Phelps is part of a conspiracy to keep other swimmers from winning. Uh no. The world isn't one on even playing field. Some people are better than others and thus get better results.

Time to spin it the other way: the only reason the US landings on Mars are successful is because of secret government technology developed out of a covertly funded program from the 1950s as part of antigravity research.

Please remember that the Schiaparelli lander was an experimental lander. The intention was to test the landing technology. So yes, it failed to land, but it was not exactly unexpected...