I’m not very big on life myself, but to me that’s only superficially what this is about. To me it seems the negative reaction you get is because “life is boring” is an expression of personal suffering first, and a judgment about an objective, intrinsic quality of the very concept of existence second. So you have to be careful when you want to argue that boredom is not an intrinsic quality of existence because you end up invalidating an expression of personal suffering, which is generally considered gauche.

Second, your arguments in favour of life not being boring generalizes conditions that may not be everyone’s. The ability to change jobs, move, find new friends, etc. is not necessarily universal. People who struggle with depression, in particular, may feel that your argument boils down to “pull yourself by your bootstraps”. People who are in situations of economic or social servitude will feel it comes from a situation of personal privilege.

I wouldn’t want to convince you that life is boring, it’s a good thing that you enjoy your existence, and the very fact that you enjoy it is a proof by example. That said, I think your approach to trying to make people find good in their own lives by convincing them sight unseen that their bad experience with it is their own fault is misguided.