There is no picture but most people have some kind of fixture in their stairwell.

It won't be safe is someone can reach it when using the staircase, so the dimensions of the staircase and the fixture matter.

Never hang a chandelier that someone is going to easily come into contact with. How high are your ceilings where the fixture will be hung and how tall is the fixture?

You always need to be sure that your ceiling around the J box is reinforced to carry the weight of whatever chandelier you choose. How heavy is the chandelier?

One would never hang a chandelier where it can be reached so not understanding.

The odds of it coming loose are zero, less than zero when someone is passing under it. But obviously it should be high enough so that no one can reach it while moving up or down the staircase. Check code requirements in your area, but otherwise I would think something like 7'-6" clearance or higher should suffice.

You are not overthinking. Here's something else to think about when cleaning time comes around. "How the he!! do I set up this ladder on these stairs?"

If you want to jazz, think about going low:

LED strip under the handrail

Strip of molding a few inches above the treads with LED strip underneath. Like a handrail but lower

Yes, chandeliers over staircases can absolutely be installed safely when the proper clearances and mounting support are considered. The key factors are ceiling height, fixture size, and ensuring the fixture is mounted high enough to avoid contact when using the stairs.

In many luxary homes we install stairwell chandeliers using reinforced mounting boxes and precise cable adjustments so the fixture hangs at the correct elevation. It's also important that the fixture can safely be accessed for cleaning and maintenance.

A qualified electrician can easily evaluate the space and recommend the right fixture and mounting height.

- Quality Service & Improvements, Electrical Contractor

I had the same struggle picking lighting for my staircase, and checking seus lighting reviews helped me feel more confident about what would actually look good in real life. The customization options were a nice bonus too, since I needed a slightly different size. Shipping was quick and the fixture felt solid once installed, so it might be worth a look if you want something modern without overthinking it.

As long as the chandelier is tied to the structure of the ceiling there shouldn't be an issue with it's falling. We cant see the exact configuration of your staircase but an electrician worth his salt should be able to figure out a mounting height that will work with your stair.