NASA intentionally completely gave up on trying to answer the Mars life question for multiple decades and only very recently has come back around to the idea of doing life finding missions.

there probably never was any there for a meaningful amount of time, but it's incredibly hard to prove a negative.

It's a touchy subject because scientists are afraid of looking like cranks. Just like cognition in other nonhuman species was historically dismissed because no one wants to be seen as someone who think plants talk to each other

It's because the more important question of "how can I personally profit from this?" usually takes precedence.