I'll give a different perspective. On the way to work one morning, just after turning onto a 4 lane busy road on my commute, I ended up stuck behind a slow pickup. I did a head check to see if the next lane was clear...
When I turned my head forward again, the pick up was nearly stopped in front of me. I was going 35 mph. I managed to lean far enough over to miss the truck. A rider behind me said my wheels were *under* the bumper of the truck as I went by it. I was unable to recover, leaning hard right into a left hand corner, and despite my best effort, went wide and hit the curb, tossing me off the bike.
Unfortunately, there was a steel light pole in my path. My left leg hit the pole and that snapped both Tib/Fib bones in my leg. Short story, they put a rod down the tibia for a few years and I healed pretty much ok, with a slight out of rotation foot from the surgeon not quite getting the bones back strait.
I rode to my second doctor appointment after being put in a walking cast. After buying a new bike, since the other one was totaled.
Thing happen on the street. We all have to manage our risks. There are many ways we do this. From when and how we ride, to the gear we wear and what types of roads we ride.
For about a year after the accident I really felt uncomfortable in high traffic situations. What made the most difference for me in regaining my confidence was taking a rider training course. It wasn't so much about riding as it was about getting a refresher in good habits and looking for hazards.
The other thing I did was to stop commuting on the bike. Commute times are the highest traffic times with the most zoned out drivers that are mostly taking the exact same route every day and are paying the least amount of attention, doing the most negative multitasking while driving and putting the least amount of thought into their driving.
If you love riding the scooter, don't give it up because of the risks, but instead choose ways to manage those risks.
I have about 500k miles of riding. Mostly motorcycles, but scooters too. I rode a Sym 150 all around Egypt, including major cities like Alexandria and Cairo. Intense doesn't begin to describe those cities!
I personally believe that conspicuity is a myth. Being seen doesn't mean people won't still do dumb things that threaten your safety. I've seen a driver pull right out in front of a fire truck. They screamed "I didn't see you" over and over when they got out of the car. 30 ton, bright red, strobes, headlights, siren and horn all going, they still "didn't see" the fire truck.
What chance would I have on a scooter of that driver seeing me? I'd say zero. Therefor, it's up to me to see THEM. Only I am responsible for my safety. I can't trust anyone else with that responsibility.
I have had people look right at me, make eye contact, then change lanes into me. We are not a threat to people in cars. Their subconscious mind often ignores us before their conscious mind can acknowledge our presence. No amount of lights or bright colors will change this. Some drivers, the most dangerous ones, will never see you.
Go take a MSF Basic Rider course. If you ask up front, they will probably let you use your scooter. It's about $100 and usually done Fri eveing, Sat and Sun. You may be surprised at the bad habits you have picked up over the years and the new concepts and ideas you learn. Regardless of how you feel at the end of the course, nearly all riders will be riding smarter and better afterwards. They offer other courses as well. Returning rider, Intermediate rider and some places offer Advanced rider courses too. Pick what you feel meets your needs.
Then see how you feel. If you still feel uncomfortable riding the scooter, then you can make that decision knowing you are making it because it's right for you, not because of any lingering fears. "what if" should not rule your decisions. Life is hazardous. But we pretty much manage to get through it anyway.
