Why are flamingos pink

Actually, flamingos are not pink. They are born with grey feathers, which gradually turn pink in the wild because of a natural pink dye called canthaxanthin that they obtain from their diet of brine shrimp and blue-green algae. Flamingos in zoos would often lose most of their pink colouration until keepers started adding synthetic canthaxanthin to their diets. In shorter terms, it's because of what they eat.

I heard its cause they eat a lot of shrimp but I dont believe it at all

I believe you thousands wouldn't

It's due to their diet.