As a social scientist and an epistemologist/philosopher of science, I'll raise you.
I'd like to point out this data is not a random sample of D&D players, but rather is biased by the sorts of players D&D Beyond is marketed towards. It's entirely possible that D&D Beyond is less likely to be used by veteran DMs and longtime grognards, and consequently, there's a false generalization that because most new/young DMs and their parties don't go beyond level 10, that ALL DMs and their parties don't. I'd hate to see WoTC not make products for people who would like higher level campaigns just because it doesn't appeal to recruitment of new players.
As a DM for over half a decade, I can attest that my campaigns typically start at level 1 and end at level 10. I actually would like to start a campaign at level 10 and end at level 20 for a change of pace, but I can't find any good resources for lessons learned at running high level campaigns.
I welcome advice, to include campaign recommendations for a DM that wants to explore high level play for the first time.
Let's see, I ran a game and played in a game that went to 20th. I'm hopeful that my current campaign to get to 20th now that I'm running a home campaign again (had to take a hiatus for 1.5 years because of moving).
At higher levels, I use a lot of custom monsters and encounters. Terrain and hazards become more important, the plot has always been be pretty earth shaking. Stopping a lich from ascending to godhood, stopping a sleeping god from being awoken while fighting the armies of a false emperor are some examples.
I do put some limitations in just for my own sanity. Planar travel is more difficult for thematic reasons and gives me an excuse to ban things like plane shift and banishment; there has to be a portal to travel between planes. I ban teleportation for similar reasons, bopping around the world using teleportation circle just isn't my style. YMMV.
Keep an eye on resources and magical items. The PCs having cool toys is part of the fun but it can be a bit overwhelming. I limit what people have access to although they can also give me a wish list so I can think about the impact.
Be flexible with PCs. Some people are just going to get tired of running the same character, I let people retrain if it's a minor tweak or let people bring in new PCs at the same level as everyone else. I've always wanted to take my PCs from 1-20, but not everyone will.
Think about how the powers that be in your region and world are going to respond to PCs that are nearly superhero level of power. Are they going to welcome them? Fear them? Try to gain their favor?
I tweak monsters, especially epic monsters. My rule of thumb is to have 1 legendary action and save less than the number of party members instead of the standard 3.
I hand wave or work with the group to develop a narrative for overcoming lower level encounters the vast majority of time.
Other than that, I think this should be a separate thread, and it still follows general advice of relationships, flexibility and making a compelling story.
