It's very clear. And since it's that clear. playing at the same table can't be an enjoyable experience for you or them!If it's not clear, the players I have problems with hold no illusions about what I think of them.
I can't think of anything more important.Except there is no trust.
For these players to pay full attention and engage in your lore to the extent that you expect? They need to trust that this will pay off.
Not that they'll "win" or succeed or whatever, but payoff in the sense that regardless of what happens it will be engaging, interesting and fun. Without that trust, even a short term campaign isn't going to be good for you or them.
Well, it's only for the summer.
How many sessions is that? In my experience, even one session where you're miserable AND these players are miserable is probably too many.