In other words, cheap lasers project a beam of a few millimeters when output, but can expand the diameter by 10-20 cm at 500 meters. If your laser pointer retains a few millimeters from 500 m to 1 km, then you have a certain quality. Most laser buyers do not care about the 00 TEM mode with holographic stability, it can be random, as long as it emits bright and distant light.
Don't actually try this. I hope this is a thought experiment, and I hope it shows that the conditions on the plane at night are incomparable with your living room at home or classroom in school. All of the above are applicable to low-power laser pointers that are considered relatively safe. You can also buy more dangerous and higher power lasers.
They are powerful enough to cause permanent damage to your eyes before you blink—and they may cause permanent damage to the pilot’s eyes. Worse of these is trying to flash the plane. I have a private pilot's license. One time when I was flying at night, someone on the ground pointed at me with a bright white light.
It may be a large flashlight or a spotlight for installation in a car or truck. The propagation speed of the beam is much faster than that of the green laser pointer beam, so it is less dangerous. Nevertheless, when the light shines on the plane I am flying, I cannot see anything else on the ground anywhere near the light.
Fortunately, the idiot who aimed at the light was not too close to the airport. After I flew past his position, the light was not visible behind me, so I could still see the airport. This is distracting enough. I never want to be flashed by a laser while flying, even a little bit.