I agree with most of what you have said - we need to exert political pressure by taking action. This action probably needs to be disruptive and unpleasant to work, like the actions taken by the civil rights movements of the last century.

However, I would also like to put forward the following argument for why your own efforts could make a difference:

Imagine a trolley, speeding toward a junction. On one branch is a child, tied to the rails.

You are in the plant room and can cut power to the trolley, but this will only slow it down - the trolley's momentum alone will kill the child. However, you see across the way a stranger in the signal box, surrounded by levers controlling the points in the station. They are frantically pulling levers, but so far they haven't hit on the one which diverts the trolley.

Should you cut the power to slow the trolley?

We are on the tracks - if we survive, it will be because of a political or technical breakthrough before it's too late. We don't know precisely when too late is - it could be ten years, or twenty, or ten years ago and we're buggered. Each individual's emissions savings make too late a little later, which changes the odds of survival a little bit (or our estimate of the odds - this is probably the philosophical weak spot in the argument).

Maybe the plane trip you don't take or the car you stop driving or the product you choose not to buy is the marginal decision that gives time to avert disaster. If we do avert disaster, one of these decisions must be that marginal decision, somewhere, somewhen.

These choices are tickets in the not-extinction lottery, and it makes sense to play when you can, as much as you can.