A lot of people really seemed to be tied to this idea that you have to justify learning ZBLL somehow, and that you should only do it if it's "worth it". Even when people state that they are learning the algs for fun, people really don't seem to be able to let go of the idea.
There are quite a few examples of people who actually did learn ZBLL just for fun, and without any intention to make it "worth it". To give some examples (only including people I've personally talked to), there is me, Callum Hales-Jepp and Micki Kanaiya Harning. As far as I know, none of us are sub 8 and definitely didn't need full ZBLL to achieve our global averages. I don't think any of us regret learning it.
If you really want encourage people not to learn ZBLL (for some reason) you should probably instead cast doubt on whether they really find it fun to learn algs. From my experience, it is actually quite rare to enjoy learning big algsets, and sometimes it's a thing you think you'd enjoy until you actually try to do it. I've seen quite a few people initially claim they like learning algs, but quickly get bored when they try to tackle something like ZBLL.