I have one simple rule when I'm jungling

Just one: if I get invaded in my jungle, I expect my nearest laners to come help me, unless they're already fighting their lane opponent.

Let's get one thing clear: whether you like it or not, this is a team game. And a team is called a team because it helps and supports its members. If you're standing around in lane with your finger up your ass while I have the enemy jungler AND your fucking lane opponent invading me, then guess what? No ganks for you. For the rest of the game. And you can kiss "your" blue/red buff goodbye too, because I'll be taking it myself. You want to be selfish and decide to not miss a few cs over helping your jungler? Fine, your jungler can be selfish too.

There's almost no excuse that forgives this offense. If you're engaged in full-on combat with your lane opponent, I can accept that, and I'll find a way to manage. But by god, if you see your lane opponent leave lane and start walking into my jungle, get your sorry ass over here and help fend off the invade. Even if I know they're coming for me and I don't die, that's still a huge amount of XP and gold I lose out on because you didn't feel obligated to leave lane.

And when the jungler falls behind, everyone else on the team automatically falls behind as well. Because a jungler who is behind has just 2 options to get them back in the game: power-farm (i.e. ignore the lanes completely and farm to the point where you're relevant again) or gank like crazy (also ill-advised because a jungler who is behind just ends up being food for the enemy laners when he ganks).

The team's objective control is also reduced if the jungler is behind, because of how smite's damage scales with level. If the team can't contest objectives, they get even further behind. In these cases the jungler is usually blamed, leaving them both confused and agitated (and thus even less likely to help the laners in the future).

So laners, please remember that this is a team game for a reason. If the jungler is being invaded, get your ass over there and help out. You'll come out of it at least 1 kill stronger, and have a very happy jungler. It's a win-win.