some people seem not to get the point of "millions of users", which presumably includes non-techies that do not use adblockers. I mean that without ads (or mining?), no instance would be able to scale to the point where it can compete with Reddit for example. If you were to want that.
The point of Lemmy is NOT to have a single instance compete with Reddit! That would just be Reddit V2 then. There just needs to be more instances to distribute the user load more evenly. Running a small/medium sized VPS costs about as much as a Netflix subscription.