What to do after reaching 20th level?

Answer 1

no more level (collecting XP)

Answer 2

don't worry brother @nikolay knows what to do
we don't need to bother about that !

Answer 3

xD imagine he gets a reset button with a star that would put him on a permanent leader board. (Like Prestige)

Then each person who prestiges will get added behind him.

Prestige twice and you'll get to move up one space :D

that would be cool