I told OP to ignore trolls, not advice
A wild caught fish cannot just be dumped into the human world with expensive equipment, it requires attention to the fish, not only the "gear".
A Tank-Takedown fish, can easily have genetic weakness, that would have ended it's life in nature even faster. In the tank it will have survived longer, covering the inherent weakness.
It is not always the tank or the aquarian who is to blame for fish death.
That is a constant human excuse: we risk to kill the fish, there is no way around that. Telling people who cannot find the cause of their fishes dying that it -must be- their fault, is not very factual.
When people are negative, without factual reason, it qualifies as trolling in most contexts.
In nature fishes spawn huge numbers. They also die constantly and have a relatively high mutation-chance compare to the mutation locked animals that never really change much.
The fish could have died from genetic weakness or damage it got from being better up and about etc etc etc.
It does not always have to be about quarantine tanks, buying medicine for ich that was never there or similar.
Fish stress.
They can die because someone watched them for too many hours and forgot they need 12h to detox - every time they are stressed by any factor.
Until the 12h has passed, nothing in their body actually work.