Calculus.
And the holodeck.
Yawn.
And boring af.
Not everyone enjoys video games
What do you want to do that can't be done on the holodeck? Calling it "video games" is really narrow minded and dismissive.
The holodeck can simulate any environment. A person can swim, mountain bike, ski, rock climb, fly, solve puzzles, play pool, play cards, whatever a person wants.
It’s not paradise. It’s a gilded cage.
Not everyone wants to be mainstream and attend Starfleet. Some want to explore on their own and do their own thing. Very little room for that unless your hobby is approved by Starfleet.
This statement is based on facts not in evidence. Really, there are few examples of non-Starfleet people and activities. The few examples we do have actually contradict your assumption. The SS Vico (NAR-18834) from TNG "Hero Worship" was not a Starfleet ship, nor were the scientists on the ship Starfleet personnel. Likewise, the USS Raven (NAR-32450) was another civilian exploration ship used by civilians to study the Borg.
Pike contemplated leaving Starfleet and becoming a civilian trader or going into business on Regulus. We see many other traders and freight operators throughout all Star Trek series.
In addition to the above civilian scientists on the Raven and Vico, we see archaelogicists like Roger Korby, the Craters, or Professor Galen. Richard Daystrom was a civilian scientist and computer engineer.
Plenty of civilians go on the adventure of colonizing new planets. This is definitely not 100% safe. Other civilians tend bar or run pleasure planets.
We run the gamut in Star Trek from blue collar bartenders, farmers, restauranteers, and construction workers to white collar professors, scientists, and politicians.
I don’t want risk. I want to work a 9-5 at the shop, come home, and tinker on my Saab. Pretty sure there’s gonna be plenty of people in the future who want the same.
What, you’re gonna exile them to the Colonies because they want to do a Star Trek version of a burnout once in a while and have some fun? Pff.
So, you can work 9-5 building starships, stomping grapes, working at a restaurant, or raising the ocean floor, then come home and tinker on your 300 year old car. And that's on Earth, not a distant colony.