I think I could confidently assume that
all of us dive for fun.

There's a lot of debate here about drills, procedures, best-practice etc... because those are topics which make interesting forum reads. Some of us also define 'fun' through the perfection of our diving technique.
When divers gain a great deal of experience, the 'novelty' of breathing compressed air tends to run out. We seek other avenues, within scuba, to progress our interest so that we keep on having fun. Examples of that may be:
1) Refining our scuba techniques.
2) Cave and Technical diving.
3) Underwater photography.
4) Collecting fossils.
5) Underwater hunting.
6) Teaching scuba to others.
7) Researching marine life and behaviour.
etc etc etc
After a few (
dozen/hundred/thousand) dives, SCUBA ceases to be the goal in itself... and becomes more of a 'vehicle' to enable other activities within the underwater environment.
We don't necessarily dive
for the sake of diving itself, but we love being underwater...and find activities that suit us...and allow us to get submerged as regularly as possible whilst still keeping the diving fresh and entertaining.