how to be less irritating?
By not using a light that is illegal in Germany.
Cheap lights are almost always:
- Powered by a very powerful battery capable of supplying a huge number of watts (to cover up the fact that the light has a poor beam pattern and instead provide so many lumens that it seems bright enough)
- Have a flashlight-style reflector that is spherically symmetric, usually produced in China for flashlights but then some idiot decided to reuse the reflector for vehicle lights
- Mounted on the handlebar using a style of mount that is prone to changing the angle of the light if riding at high speed over bumps, instead of proper mounting hardware for fork crown that is held with tight bolts to keep the angle of the light fixed
- For extra points, have a blinking mode to save battery life and irritate other road users
These cheap lights are excellent in blinding oncoming people. The only possibility you can see forward is to direct the brightest part of the beam far away in the road. This means a large portion of the spherically symmetric pattern is projected above the horizon, blinding oncoming riders.
However, the cheap lights are usually poor for seeing because the beam pattern is not designed for vehicle use. The spherical pattern directs too much light where not needed and too little light where needed.
The Germans have a solution for this: their law, StVZO, requires lights to be non-blinking, powered by a power source that doesn't suddenly go away (=dynamo), and the beam pattern to be such that it lights the road ahead of the cyclist and only the road ahead of the cyclist, having a sharp cut-off at the beam to not direct any part of the bright beam above the horizon (there will be still plenty of spill light that won't blind others but allows car drivers to see there's a bike).
Unfortunately quality costs. Only about 1% of people live in Germany, so pretty much the Germans are designing lights only for 1% of the population. If a German quality headlight manufacturer can amortize the product development costs of a true vehicle headlight over 1% of cyclists in this planet and a Chinese manufacturer can amortize the product "development" (in quotes because reusing flashlight technology doesn't really require any intelligent work) costs of a flashlight over 99% of cyclists in this planet, guess which light will be more expensive and which will be less expensive?