Chili peppers is actually really interesting. Their heat is strictly meant not to deter predators, but to select them. Birds have no problems eating chilis because capsaicin does not target them, because they are their primary seed dispersers. But mammals tend to chew up seeds so we’re normally much less useful to the plant for seed dispersal, so they evolved capsaicin to keep us from wasting their seeds.

Though you can argue that capsaicin is even more successful because humans like the taste, since we now actively plant chilis everywhere, giving them water and nutrients and removing competing plants. Look at how fast it went from not even existing in Asia to being one of the most important spices on the continent.