What you do at your own table at home isn't advertising, especially if you are playing a legacy edition that they aren't selling things for anyway.
yes and no.
You go to a friends house with 4 other friends, don't tell anyone what you are doing, and leave and never speak of it until next game is the CLOSEST you get to not keeping it in the public eye (but players come and go players become DMs someday and bring in new players)
MORE likely you sit down with 4-6 friends joke around talk about gaming and play... when you are there most likely those closest to you know it's D&D night (again unless you keep it secret, or lie) and the idea of "Oh I know someone that plays D&D" spreads slowly.
Now if 1 group does this will it mean anything... I doubt it, we are at butterfly wings here... but it 3% of the playerbase CHANGES to other things if instead of D&D night they call it TORG night, or Vampire night, or what ever... and when people say "Like D&D?" (and they will) correct them "Only the same way a poker night and a monopoly night are the same cause the are both games, this is ______" that is a VERY minor hit to Wotc.
Now if you splinter that 3% over 11 game systems no 1 of them is getting a big boost, but all 11 get a minor boost and WotC/D&D take a minor hit.
This isn't the only way. It's not what I am going to do. It is however the only way to not enhance the IP...
Someone said they run a D&D gaming club at school. Changing to Level Up or Pathfinder might feel good, but they are still variants of D&D. Changing to Rifts gaming club is a much bigger blow then changing to (insert 3rd party variant that is still D&D) or (insert previous edition).
IT's like "Sticking it to marvel" by not reading any more spiderman or avengers comics... and watching spiderman and the avengers on Disney plus, or going to see the new Deadpool and Wolverine movie. You moved your money from 1 part of Disney to another... and if you still walk around with your iron man and or spider man shirt on, you keep the IP in everyone's mind and enhance the brand some small bit.
We know what Hasbro wants... they actually told us. The IP for D&D. If the movie and a new cartoon and some comics and those toys all sell well they don't care that we are playing pathfinder... just that we still call ourselves D&D players and make D&D as a brand, as an IP stronger.