good question.

what do i gain?

you see, when a car from behind hi beam at you, they either want you to speed up, finish the overtaking and shift to left lane so they can drive smoothly on the right lane at 180km/h, or they want you to shift to the left lane before you do the overtaking. in short, they want you to get out of their way.

you are on the right lane for a reason, right? we are not hogging the right lane at 80km/h.

so by hi beam at you and ask you to give way, they are trying to dictate how you should drive and this is dangerous to you.

so what i do is, i slow down and let them overtake me.
there are many impatient asssholes after hi beam, they try to overtake you from the left lane, if you shift to the left it will cause accident as they are taking the left lane too.

so the best way is to slow down, keep driving on the right and let them overtake from the left.

as for tailgating, their purpose is to put pressure on you so you give way, this is also dangerous, is a form of road bully too.