Because you said it was unbelievable to you.
You cannot say something in a public square and complain that people call you out on it, correct you on it, or questioned it.
The Sarlacc surviving that is 100% in line with the lore of Star Wars. There are animals that can survive with holes in their stomach in the real world.
Therefore, you finding it unbelievable makes zero sense because you have nothing to base that on. The lore does not support you. Reality does not support you. Here is the thing, I am okay with you saying it was "unbelievable" but when people point out that it isn't, rather than admit your assumption was wrong. You turn around a play semantics.
This is a pattern with you. No one can win any argument with you because you will always move a goal post or two.